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  • 1. Abletshauser, C
    et al.
    Klüssendorf, D
    Schmidt, A
    Winkler, K
    März, W
    Buddecke, E
    Malmsten, M
    YKI – Ytkemiska institutet.
    Biosensing of arteriosclerotic nanoplaque formation and interaction with an HMG-CoA reductase inhibitor2002Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 176, s. 131-146Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Proteoheparan sulphate can be adsorbed to a methylated silica surface in a monomolecular layer via its transmembrane hydrophobic protein core domain. As a result of electrostatic repulsion, its anionic glycosaminoglycan side chains are stretched out into the blood substitute solution, thereby representing one receptor site for specific lipoprotein binding through basic amino acid-rich residues within their apolipoproteins. The binding process was studied by ellipsometric techniques suggesting that high-density lipoprotein (HDL) has a high binding affinity and a protective effect on interfacial heparan sulphate proteoglycan layers with respect to low-density lipoprotein (LDL) and Ca2+ complexation. Low-density lipoprotein was found to deposit strongly at the proteoheparan sulphate-coated surface, particularly in the presence of Ca2+, apparently through complex formation 'proteoglycan-LDL-calcium'. This ternary complex build-up may be interpreted as arteriosclerotic nanoplaque formation on the molecular level responsible for the arteriosclerotic primary lesion. On the other hand, HDL bound to heparan sulphate proteoglycan protected against LDL deposition and completely suppressed calcification of the proteoglycan-lipoprotein complex. In addition, HDL was able to decelerate the ternary complex deposition. Therefore, HDL attached to its proteoglycan receptor sites is thought to raise a multidomain barrier, selection and control motif for transmembrane and paracellular lipoprotein uptake into the arterial wall. Although much remains unclear regarding the mechanism of lipoprotein depositions at proteoglycan-coated surfaces, it seems clear that the use of such systems offers possibilities for investigating lipoprotein deposition at a 'nanoscopic' level under close to physiological conditions. In particular, Ca2+-promoted LDL deposition and the protective effect of HDL even at high Ca2+ and LDL concentrations agree well with previous clinical observations regarding risk and beneficial factors for early stages of atherosclerosis. Considering this, the system was tested on its reliability in a biosensor application in order to unveil possible acute pleiotropic effects of the lipid lowering drug fluvastatin. The very low-density lipoprotein (VLDL)/intermediate-density lipoprotein (IDL)/LDL plasma fraction from a high risk patient with dyslipoproteinaemia and type 2 diabetes mellitus showed beginning arteriosclerotic nanoplaque formation already at a normal blood Ca2+ concentration, with a strong increase at higher Ca2+ concentrations. Fluvastatin, whether applied to the patient (one single 80 mg slow release matrix tablet) or acutely in the experiment (2.2 μmol L-1), markedly slowed down this process of ternary aggregational nanoplaque complexation at all Ca2+ concentrations used. This action resulted without any significant change in lipid concentrations of the patient. Furthermore, after ternary complex build-up, fluvastatin, similar to HDL, was able to reduce nanoplaque adsorption and size. These immediate effects of fluvastatin have to be taken into consideration while interpreting the clinical outcome of long-term studies.

  • 2.
    Al-Khalili, L
    et al.
    Department of Surgical Science, Karolinska Institutet, Stockholm, Sweden; Dept. of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; Integrative Physiology, Dept. of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
    Krämer, D
    Department of Surgical Science, Karolinska Institutet, Stockholm, Sweden; Dept. of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
    Wretenberg, Per
    Region Örebro län. Department of Surgical Science, Karolinska Institutet, Stockholm, Sweden.
    Krook, A
    Department of Surgical Science, Karolinska Institutet, Stockholm, Sweden Dept. of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
    Human skeletal muscle cell differentiation is associated with changes in myogenic markers and enhanced insulin-mediated MAPK and PKB phosphorylation2004Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 180, nr 4, s. 395-403Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    AIM: We hypothesized that myogenic differentiation of HSMC would yield a more insulin responsive phenotype.

    METHODS: We assessed expression of several proteins involved in insulin action or myogenesis during differentiation of primary human skeletal muscle cultures (HSMC).

    RESULTS: Differentiation increased creatine kinase activity and expression of desmin and myocyte enhancer factor (MEF)2C. No change in expression was observed for big mitogen-activated protein kinase (BMK1/ERK5), MEF2A, insulin receptor (IR), hexokinase II, and IR substrates 1 and 2, while expression of glycogen synthase, extracellular signal-regulated kinase 1 and 2 (ERK1/2 MAP kinase) and the insulin responsive aminopeptidase increased after differentiation. In contrast to protein kinase B (PKB)a, expression of (PKB)b increased, with differentiation. Both basal and insulin-stimulated PI 3-kinase activity increased with differentiation. Insulin-mediated phosphorylation of PKB and ERK1/2 MAP kinase increased after differentiation.

    CONCLUSION: Components of the insulin-signalling machinery are expressed in myoblast and myotube HSMC; however, insulin responsiveness to PKB and ERK MAP kinase phosphorylation increases with differentiation.

  • 3.
    Andersson, Eva A
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Nilsson, Johnny
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Thorstensson, Alf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Intramuscular EMG from the hip flexor muscles during human locomotion.1997Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 161, nr 3, s. 361-70Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose was to investigate the activation pattern of five major hip flexor muscles and its adaptation to changing speed and mode of progression. A total of 11 healthy subjects performed walking and running on a motor-driven treadmill at speeds ranging from 1.0 to 6.0 m s-1. Intramuscular fine-wire electrodes were used to record myoelectric signals from the iliacus, psoas, sartorius, rectus femoris and tensor fascia latae muscles. The basic pattern, with respect to number of activation periods, remained the same irrespective of speed and mode of progression. However, differences in the relative duration and timing of onset of activation occurred between individual muscles. Over the speed range in walking, a progressively earlier onset was generally seen for the activation period related to hip flexion. Changes in EMG amplitude were measured in the iliacus and psoas muscles and showed a marked increase and difference between walking and running at speeds above 2.0 m s-1. Thus, the alternating flexion-extension movements at the hip during locomotion appear to be governed by a rather fixed 'neural program' which normally only needs minor modulations to accomplish the adjustments accompanying an increase in speed of progression as well as a change from walking to running.

  • 4. Andersson, R. M.
    et al.
    Aizman, O.
    Aperia, A.
    Brismar, Hjalmar
    KTH, Tidigare Institutioner, Fysik.
    Modulation of Na+,K+-ATPase activity is of importance for RVD2004Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 180, nr 4, s. 329-334Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aim: This study was performed to examine the role of Na+,K+-ATPase activity for the adaptive response to cell swelling induced by hypoosmoticity, i.e. the regulatory volume decrease (RVD). Methods: The studies were performed on COS-7 cells transfected with rat Na+,K+-ATPase. To study changes in cell volume, cells were loaded with the fluorescent dye calcein and the intensity of the dye, following exposure to a hypoosmotic medium, was recorded with confocal microscopy. Results: Ouabain-mediated inhibition of Na+,K+-ATPase resulted in a dose dependent decrease in the rate of RVD. Total Rb-86(+) uptake as well as ouabain dependent Rb-86(+) uptake, used as an index of Na+,K+-ATPase dependent K+ uptake, was significantly increased during the first 2 min following exposure to hypoosmoticity. Since protein kinase C (PKC) plays an important role in the modulation of RVD, a study was carried out on COS-7 cells expressing rat Na+,K+-ATPase, where Ser23 in the catalytic alpha1 subunit of rat Na+,K+-ATPase had been mutated to Ala (S23A), abolishing a known PKC phosphorylation site. Cells expressing S23A rat Na+,K+-ATPase exhibited a significantly lower rate of RVD and showed no increase in Rb-86(+) uptake during RVD. Conclusion: Taken together, these results suggest that a PKC-mediated transient increase in Na+,K+-ATPase activity plays an important role in RVD.

  • 5. Andersson, Staffan
    et al.
    Kronström, A
    Department of Clinical Physiology, Umeå university.
    Hentschel, J
    Department of Clinical Physiology, Umeå university.
    Wall mechanics of the rat bladder. II. Hydrodynamic studies in the frequency domain1988Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 134, nr 4, s. 463-466Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The hydrodynamic properties of the urinary bladder in rat were examined by means of very small periodic changes in volume at different frequencies. The elastance increased with increasing frequency of volume changes, indicating the presence of viscoelastic elements. When the bladder was only moderately distended the influence of viscosity was minor. We consider that the rat bladder examined by this technique is an ideal experimental model for assessment of in vivo effects of pharmacological agents on bladder wall tonus. For example, cholinergic treatment showed a 100% increase in elastance and atropine inhibited this effect completely within 3 min.

  • 6. Andersson, Staffan
    et al.
    Kronström, A
    Department of Clinical Physiology, Umeå university.
    Teien, D
    Department of Clinical Physiology, Umeå university.
    Wall mechanics of the rat bladder. I. Hydrodynamic studies in the time domain.1988Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 4, nr 457-461, s. 5-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The hydrodynamic properties of the rat bladder in the collection phase were examined by slow continuous and very fast stepwise cystometry in nine rats. In vivo, the fast volume steps induced a reproducible detrusor contraction (type A) which remained after spinal anaesthesia and anticholinergic treatment, but ceased post-mortally within 1 h. No significant effect of anticholinergic treatment was found on bladder stiffness. The stiffness and relaxation time of the bladder wall increased markedly at large distension. At small and moderate distension, however, the compliances evaluated from continuous and stepwise cystometry were nearly the same, and a linear elastic model of the bladder was applicable. We consider that the rat bladder will be a useful experimental model in further research on viscoelasticity and instability of the bladder wall.

  • 7.
    Axelson, Hans W
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Klinisk neurofysiologi.
    Human motor compensations for thixotropy-dependent changes in muscular resting tension after moderate joint movements2004Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 182, nr 3, s. 295-304Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    AIM:

    This study on healthy subjects explores history-dependent changes in the resting tension of relaxed wrist muscles after moderate joint excursions and the motor control consequences of these changes during voluntary wrist joint position maintenance.

    METHODS:

    Integrated surface electromyogram (IEMG) was recorded from wrist extensor/flexor muscles. Angular position and torque were recorded from the wrist joint. Changes in wrist flexor muscle resting tension were sensed by a force transducer pressed against the tendons.

    RESULTS:

    Consecutive stepwise changes (7.5 degrees ) in wrist joint position (within the dorsiflexed range) were either imposed on relaxed subjects or actively performed while the subjects under visual guidance tried to mimic the passive movements. In relaxed subjects, passive joint torque resistance at a given steady dorsiflexed position either gradually declined or rose depending on the direction of the previous transition movements. In corresponding voluntary contraction experiments, the IEMG amplitude from position holding wrist extensors was found to vary in a similar way as the passive torque resistance. Further, there was a strong correlation between history-dependent changes in extensor IEMG amplitude and stress alterations exhibited by the relaxed antagonist flexors. The above described, slowly subsiding post-movement mechanical and motor adaptations were accelerated by brief forceful cocontractions of the forearm muscles.

    CONCLUSION:

    Moderate stepwise changes in joint position are sufficient to induce history-dependent after-effects in passive muscular resting tension, after-effects which during voluntary position holding are effectively compensated for by the motor control system.

  • 8. Baer, R
    et al.
    Eiken, Ola
    Karolinska Institutet.
    Effects of continuous positive- and negative-pressure breathing on the pattern of breathing in man during exercise.1989Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 137, nr 2, s. 301-7Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Breathing pattern and static lung volumes were studied in 10 subjects at rest and during incremental-load cycle ergometry under three different conditions, viz. with normal pressure in the airways (control) and during continuous positive- and negative-pressure breathing (CPPB, CNPB) of +15 and -15 cmH2O. End-expiratory, end-inspiratory and mid-expiratory volumes were increased by CPPB and decreased by CNPB; these effects were especially pronounced at rest and during mild exercise. Both at rest and during exercise mean inspiratory flow (VT/TI) was exaggerated by CPPB and attenuated by CNPB. At rest these changes were due mainly to concomitant changes in tidal volume (VT) which was increased by CPPB and decreased by CNPB, while inspiratory time duration (TI) was relatively unaffected by pressure breathing. The transition from rest to loadless pedalling induced an increase in VT but no change in TI in the control condition, whereas in the CPPB and CNPB conditions TI decreased and VT remained unaltered. This CPPB- and CNPB-induced change in the volume-time threshold relationship at the onset of pedalling is attributed to increased stretch receptor activity in the extrathoracic portion of the trachea as a result of the increments in transmural pressure. During the course of exercise there was an inverse relationship between the slope of the VT-TI curve and the mid-expiratory volume in that the slope was greater in the control than in the CPPB condition and greatest during CNPB, suggesting that in exercise hyperpnoea the VT-TI relationship is also determined by pulmonary and/or thoracic wall stretch receptors capable of sensing the absolute lung volume.

  • 9. Bakkman, L.
    et al.
    Sahlin, K.
    Holmberg, H-C.
    Tonkonogi, Michail
    Högskolan Dalarna, Akademin Utbildning, hälsa och samhälle, Idrotts- och hälsovetenskap.
    Quantitative and qualitative adaptation of human skeletal muscle mitochondria to hypoxic compared to normoxic training at the same relative work rate2007Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 190, nr 3, s. 243-251Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aim: To investigate if training during hypoxia (H) improves the adaptation of muscle oxidative function compared with normoxic (N) training performed at the same relative intensity.

    Method: Eight untrained volunteers performed one-legged cycle training during 4 weeks in a low-pressure chamber. One leg was trained under N conditions and the other leg under hypobaric hypoxia (526 mmHg) at the same relative intensity as during N (65% of maximal power output, Wmax). Muscle biopsies were taken from vastus lateralis before and after the training period. Muscle samples were analysed for the activities of oxidative enzymes [citrate synthase (CS) and cytochrome c oxidase (COX)] and mitochondrial respiratory function.

    Results: W max increased with more than 30% over the training period during both N and H. CS activity increased significantly after training during N conditions (+20.8%, P < 0.05) but remained unchanged after H training (+4.5%, ns) with a significant difference between conditions (P < 0.05 H vs. N). COX activity was not significantly changed by training and was not different between exercise conditions [+14.6 (N) vs. -2.3% (H), ns]. Maximal ADP stimulated respiration (state 3) expressed per weight of muscle tended to increase after N (+31.2%, P < 0.08) but not after H training (+3.2%, ns). No changes were found in state four respiration, respiratory control index, P/O ratio, mitochondrial Ca2+ resistance and apparent Km for oxygen.

    Conclusion: The training-induced increase in muscle oxidative function observed during N was abolished during H. Altitude training may thus be disadvantageous for adaptation of muscle oxidative function.

  • 10. Balsom, Paul D
    et al.
    Gaitanos, G C
    Söderlund, Karin
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Ekblom, Björn
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Björn Ekbloms forskningsgrupp.
    High-intensity exercise and muscle glycogen availability in humans.1999Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 165, nr 4, s. 337-45Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study investigated the effects of muscle glycogen availability on performance and selected physiological and metabolic responses during high-intensity intermittent exercise. Seven male subjects completed a regimen of exercise and dietary intake (48 h) to either lower and keep low (LOW-CHO) or lower and then increase (HIGH-CHO) muscle glycogen stores, on two separate occasions at least a week apart. On each occasion the subjects completed a short-term (<10 min) and prolonged (>30 min) intermittent exercise (IEX) protocol, 24 h apart, which consisted of 6-s bouts of high-intensity exercise performed at 30-s intervals on a cycle ergometer. Glycogen concentration (mean +/- SEM) in m. vastus lateralis before both IEx(short) and IEx(long) was significantly lower following LOW-CHO [180 (14), 181 (17) mmol kg (dw)(-1)] compared with HIGH-CHO [397 (35), 540 (25) mmol kg (dw)(-1)]. In both IEx(short) and IEx(long), significantly less work was performed following LOW-CHO compared with HIGH-CHO. In IEx(long), the number of exercise bouts that could be completed at a pre-determined target exercise intensity increased by 265% from 111 (14) following LOW-CHO to 294 (29) following HIGH-CHO (P < 0.05). At the point of fatigue in IEx(long), glycogen concentration was significantly lower with the LOW-CHO compared with HIGH-CHO [58 (25) vs. 181 (46) mmol kg (dw)(-1), respectively]. The plasma concentrations of adrenaline and nor-adrenaline (in IEx(short) and IEx(long)), and FFAand glycerol (in IEx(long)), increased several-fold above resting values with both experimental conditions. Oxygen uptake during the exercise periods in IEx(long), approached 70% of Vo2max. These results suggest that muscle glycogen availability can affect performance during both short-term and more prolonged high-intensity intermittent exercise and that with repeated exercise periods as short as 6 s, there can be a relatively high aerobic contribution.

  • 11. Berg, H.E
    et al.
    Tedner, B
    Tesch, P.A
    Changes in lower limb muscle cross-sectional area and tissue fluid volume after transition from standing to supine1993Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 148, nr 4, s. 379-385Artikkel i tidsskrift (Fagfellevurdert)
  • 12. Berg, H.E
    et al.
    Tesch, P.A
    Changes in muscle function in response to 10 days of lower limb unloading in humans1996Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 157, nr 1, s. 63-70Artikkel i tidsskrift (Fagfellevurdert)
  • 13.
    Bergfors, M
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Biologi, miljö- och geovetenskap. Umeå universitet, Medicinsk fakultet, Folkhälsa och klinisk medicin, Medicin.
    Barnekow-Bergkvist, M
    Kalezic, N
    Umeå universitet, Medicinsk fakultet, Kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Lyskov, E
    Eriksson, Jan
    Umeå universitet, Medicinsk fakultet, Folkhälsa och klinisk medicin, Medicin.
    Short-term effects of repetitive arm work and dynamic exercise on glucose metabolism and insulin sensitivity.2005Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 183, nr 4, s. 345-356Artikkel i tidsskrift (Fagfellevurdert)
  • 14. Bergfors, M
    et al.
    Barnekow-Bergkvist, M
    Kalezic, N
    Lyskov, E
    Eriksson, Jan W
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinska vetenskaper, Endokrin diabetes och metabolism.
    Short-term effects of repetitive arm work and dynamic exercise on glucose metabolism and insulin sensitivity.2005Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 183, nr 4, s. 345-56Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    AIM: To determine whether repetitive arm work, with a large component of static muscle contraction alters glucose metabolism and insulin sensitivity.

    METHOD: Euglycemic clamps (2 h) were started in ten healthy individuals 15 min after 37 min periods of: (1) repetitive arm work in a simulated occupational setting; (2) dynamic concentric exercise on a cycle ergometer at 60% of VO(2max) and (3) a resting regime as a control. During the experimental periods, blood samples were collected, blood pressure was measured repeatedly and electrocardiogram (ECG) was recorded continuously. During the clamps, euglycemia was maintained at 5 mmol l(-1) and insulin was infused at 56 mU m(-2) min(-1) for 120 min.

    RESULTS: The insulin-mediated glucose disposal rate (M-value) for the steady-state period (60-120 min) of the clamp, tended to be lower following arm work than for both cycling and resting regimes. When dividing the steady-state period into 20-min intervals, the insulin sensitivity index (ISI) was significantly lower for arm work compared with the resting control situation between 60-80 min (P = 0.04) and 80-100 min (P = 0.01), respectively. Catecholamines increased significantly for arm work and cycling compared with resting regime. Data from heart rate variability (HRV) measurements indicated significant sympathetic activation during repetitive arm work.

    CONCLUSION: The results indicate that repetitive arm work might acutely promote insulin resistance, whereas no such effect on insulin resistance was produced by dynamic concentric exercise.

  • 15. Bergfors, M
    et al.
    Barnekow-Bergkvist, Margareta
    Högskolan i Gävle, Belastningsskadecentrum.
    Kalezic, Nebojsa
    Högskolan i Gävle, Belastningsskadecentrum.
    Lyskov, Eugene
    Högskolan i Gävle, Belastningsskadecentrum.
    Eriksson, J W
    Short-term effects of repetitive arm work and dynamic exercise on glucose metabolism and insulin sensitivity.2005Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 183, nr 4, s. 345-356Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aim: To detennine whether repetitive ann work, with a large component of static muscle contraction alters glucose metabolism and insulin sensitivity.

    Methad: Euglycemic clamps (2h) were started in ten healthy individuals 15 minutes after 37 minute periods of: 1) repetitive ann work in a simulated occupational setting; 2) dynamic concentric exercise on a cycle ergometer at 60% OfVO2 max and 3) a resting regime as a control. During the experimental periods, blood samples were collected, blood pressure was measured repeatedly and electrocardiogram (ECG) wasrecorded continuously. During the clamps, euglycemia was maintained at 5 mmo1/l and insulin was infused at 56 mU/m2/min for 120 min.

    Results: The insulin-mediated glucose disposal rate (M-value) for the steady state period (60- 120 min) of the clamp, tended to be lower following ann work than for both cycling and resting regimes. When dividing the steady state period into 20-minute intervals, the insulin sensitivity index, (ISI) was significantly lower for ann work compared with the resting control situation between 60-80 minutes (p=0.04) and 80-100 minutes (p=0.01) respectively.

    Catecholamines increased significantly for ann work and cycling compared with resting regime. .Data from heart rate variability (HRV) me asurements indicated significant sympathetic activation during repetitive ann work test.

    Canelusian: The results indicate that repetitive ann work might acutely promote insulin resistance, whereas no such effect on insulin resistance was produced by dynamic concentric exercise.

  • 16. Berglund, B
    et al.
    Gennser, Mikael
    Swedish Defence Research Agency.
    Ornhagen, H
    Ostberg, C
    Wide, L
    Erythropoietin concentrations during 10 days of normobaric hypoxia under controlled environmental circumstances.2002Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 174, nr 3, s. 225-229Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Serum erythropoietin levels (s-[epo]), haemoglobin concentration ([Hb]), haematocrit (hct), and ferritin concentration ([fer]) were measured in seven healthy male volunteers (20-23 years) exposed continuously to hypoxia (PO(2) 14 kPa) for 10 days. Serum erythropoietin concentration increased significantly from 9.5 +/- 3.51 to 33.6 +/- 11.64 U L(-1) (P < 0.05) after 2 days of hypoxia. Thereafter, s-[epo] decreased. However, after 10 days s-[epo] was 18.7 +/- 5.83 U L(-1) which was still increased above the pre-hypoxia level (P < 0.05). Serum haemoglobin concentration and hct increased over the 10 days of hypoxia, [Hb] from 152 +/- 8.9 to 168 +/- 9.2 gL(-1) (P < 0.001), and hct from 43 +/- 2.4 to 49 +/- 2.6% (P < 0.001). Ferritin concentration decreased significantly during the hypoxic exposure from 82 +/- 46.9 to 44 +/- 31.7 mmol L(-1) after 10 days (P < 0.01). In conclusion, the initial increase of s-[epo] under controlled normobaric hypoxia was marked, 353%, and levelled off after 5-10 days at 62-97% above normoxia level. There was also a significant increase in [Hb] and hct and a decrease in [fer] after 10 days of exposure to normobaric hypoxia.

  • 17.
    Bjarnegård, Niclas
    et al.
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och hälsa.
    Ahlgren, AR
    Sonesson, B
    Länne, Toste
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och hälsa, Fysiologi. Östergötlands Läns Landsting, Hjärtcentrum, Thorax-kärlkliniken.
    The effect of sympathetic stimulation on proximal brachial artery mechanics in humans - differential behaviour within the length of the brachial artery?2004Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 182, nr 1, s. 21-27Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aims: The mechanical properties of arteries play a major role in the regulation of blood pressure and cardiac performance. The effect of sympathetic stimulation on the mechanical properties of the proximal brachial artery was analysed in 18 healthy volunteers, nine young (25 +/- 2 years) and nine elderly (69 +/- 2 years). Methods: A non-invasive ultrasonic echo-tracking system for measurement of systolic/diastolic variation of the proximal brachial artery diameter in combination with intra-arterial pressure measurements was used to determine wall mechanics. The pressure-diameter (P-D) relationship, distensibility coefficient (DC), compliance coefficient (CC) and stiffness(beta) were obtained at rest and during sympathetic stimulation induced by lower body negative pressure (LBNP). Results: The peripheral vascular resistance increased by 100 and 72%, respectively in the young and elderly during LBNP (P < 0.001). Simultaneously, the mechanical properties of the proximal brachial artery remained unaltered, as estimated from both P-D relationship and stiffness in young (beta-index rest: 5.2 +/- 0.9, LBNP: 5.5 +/- 1.3, NS) as well as elderly (beta-index rest: 13.6 +/- 4.6, LBNP: 16.1 +/- 4.7, NS). Conclusions: LBNP-induced sympathetic activation does not change proximal brachial artery mechanics, in contrast to earlier reports on the muscular distal brachial artery. This may imply that the transition between elastic and muscular artery behaviour is within the length of the brachial artery, where the site of transition from elastic to muscular wall structure needs to be specified in future studies.

  • 18.
    Bjarnegård, Niclas
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa. Linköpings universitet, Hälsouniversitetet.
    Rydén Ahlgren, Å.
    Department of Clinical Physiology, Malmö University Hospital, Malmö, Sweden .
    Sonesson, B.
    Department of Vascular Surgery, Malmö University Hospital, Malmö, Sweden.
    Länne, Toste
    Linköpings universitet, Institutionen för medicin och hälsa, Fysiologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Hjärtcentrum, Thorax-kärlkliniken.
    The effect of sympathetic stimulation on proximal brachial artery mechanics in humans: differential behaviour within the length of the brachial artery2004Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 182, nr 1, s. 21-27Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aims: The mechanical properties of arteries play a major role in the regulation of blood pressure and cardiac performance. The effect of sympathetic stimulation on the mechanical properties of the proximal brachial artery was analysed in 18 healthy volunteers, nine young (25 ± 2 years) and nine elderly (69 ± 2 years).

    Methods: A non-invasive ultrasonic echo-tracking system for measurement of systolic/diastolic variation of the proximal brachial artery diameter in combination with intra-arterial pressure measurements was used to determine wall mechanics. The pressure–diameter (P–D) relationship, distensibility coefficient (DC), compliance coefficient (CC) and stiffness(β) were obtained at rest and during sympathetic stimulation induced by lower body negative pressure (LBNP).

    Results: The peripheral vascular resistance increased by 100 and 72%, respectively in the young and elderly during LBNP (P < 0.001). Simultaneously, the mechanical properties of the proximal brachial artery remained unaltered, as estimated from both P–D relationship and stiffness in young (β-index rest: 5.2 ± 0.9, LBNP: 5.5 ± 1.3, NS) as well as elderly (β-index rest: 13.6 ± 4.6, LBNP: 16.1 ± 4.7, NS).

    Conclusions: LBNP-induced sympathetic activation does not change proximal brachial artery mechanics, in contrast to earlier reports on the muscular distal brachial artery. This may imply that the transition between elastic and muscular artery behaviour is within the length of the brachial artery, where the site of transition from elastic to muscular wall structure needs to be specified in future studies.

  • 19.
    Björnström, Karin
    et al.
    Linköpings universitet, Institutionen för medicin och vård, Anestesiologi. Linköpings universitet, Institutionen för medicin och vård, Farmakologi. Linköpings universitet, Hälsouniversitetet.
    Sjölander, Anita
    Division of Experimental Pathology, Lund University, Malmö, Sweden.
    Schippert, Åsa
    Linköpings universitet, Institutionen för biomedicin och kirurgi, Cellbiologi. Linköpings universitet, Hälsouniversitetet.
    Eintrei, Christina
    Linköpings universitet, Institutionen för medicin och vård, Anestesiologi. Linköpings universitet, Institutionen för medicin och vård, Farmakologi. Linköpings universitet, Hälsouniversitetet.
    A tyrosine kinase regulates propofol-induced modulation of the β-subunit of the GABAA receptor and release of intracellular calcium in cortical rat neurones2002Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 175, nr 3, s. 227-235Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Propofol, an intravenous anaesthetic, has been shown to interact with the β-subunit of the γ-amino butyric acidA (GABAA) receptor and also to cause changes in [Ca2+]i. The GABAA receptor, a suggested target for anaesthetics, is known to be regulated by kinases. We have investigated if tyrosine kinase is involved in the intracellular signal system used by propofol to cause anaesthesia. We used primary cell cultured neurones from newborn rats, pre-incubated with or without a tyrosine kinase inhibitor before propofol stimulation. The effect of propofol on tyrosine phosphorylation and changes in [Ca2+]i were investigated. Propofol (3 μg mL−1, 16.8 μM) increased intracellular calcium levels by 122 ± 34% (mean ± SEM) when applied to neurones in calcium free medium. This rise in [Ca2+]i was lowered by 68% when the cells were pre-incubated with the tyrosine kinase inhibitor herbimycin A before exposure to propofol (P < 0.05). Propofol caused an increase (33 ± 10%) in tyrosine phosphorylation, with maximum at 120 s, of the β-subunit of the GABAA-receptor. This tyrosine phosphorylation was decreased after pre-treatment with herbimycin A (44 ± 7%, P < 0.05), and was not affected by the absence of exogenous calcium in the medium. Tyrosine kinase participates in the propofol signalling system by inducing the release of calcium from intracellular stores and by modulating the β-subunit of the GABAA-receptor.

  • 20.
    Blomstrand, Eva
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Eva Blomstrands forskningsgrupp.
    Celsing, F
    Newsholme, E A
    Changes in plasma concentrations of aromatic and branched-chain amino acids during sustained exercise in man and their possible role in fatigue.1988Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 133, nr 1, s. 115-21Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The plasma concentrations of branched-chain and aromatic amino acids have been measured in two different types of sustained dynamic exercise. Twenty-two subjects participated in the 1986 Stockholm Marathon and eight subjects took part in an army training programme of approximately 1.5-h duration. Both types of exercise caused a significant decrease in the plasma concentration of branched-chain amino acids, while there was no change in the concentration of total (free plus bound to albumin) tryptophan. The plasma concentration of free tryptophan, which was measured in the marathon runners, was found to increase 2.4-fold during the race. This increase is probably caused by a pronounced elevation in the concentration of plasma free fatty acids during exercise, since these are known to displace tryptophan from albumin. The observed increase in plasma free tryptophan concentration, together with the decrease in plasma concentration of branched-chain amino acids, gives rise to a marked increase in the plasma concentration ratio of free tryptophan/branched-chain amino acids. This should lead to an increase in the rate of transport of tryptophan across the blood-brain barrier and hence to an increase in the rate of synthesis of 5-hydroxytryptamine (5-HT) in the brain. An elevated concentration of 5-HT in specific areas of the brain may be responsible, at least in part, for the development of physical, and/or mental fatigue during prolonged exercise.

  • 21.
    Blomstrand, Eva
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Eva Blomstrands forskningsgrupp.
    Essén-Gustavsson, B
    Influence of reduced muscle temperature on metabolism in type I and type II human muscle fibres during intensive exercise.1987Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 131, nr 4, s. 569-74Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Six male subjects performed intensive cycle exercise to exhaustion after cooling their legs in water at 10-12 degrees C (muscle temperature (Tm) 28 +/- 2.6 degrees C, mean +/- SD). Exercise at exactly the same rate and duration (370 +/- 34 W, 1.5 +/- 0.2 min) was then repeated by each subject 2-5 weeks later at normal Tm (35 +/- 1.0 degrees C). Muscle biopsies were taken from the vastus lateralis muscle at rest and after exercise. The muscle tissue was freeze-dried and fragments of single fibres were dissected out. The fibres were classified and pooled into groups of type I and type II. Analyses of glycogen, glucose 6-phosphate, lactate and phosphagens were performed on pools of type-identified fibres. After exercise at reduced Tm, all subjects had higher concentrations of glucose 6-phosphate and lactate in both type I and type II fibres, and in most subjects the concentrations of ATP and phosphocreatine were lower as compared with the findings after exercise at normal Tm. During exercise the glycogen content of both fibre types decreased to a greater extent at reduced than at normal Tm in most subjects. The results suggest that during intensive dynamic exercise at reduced Tm there is a higher degree of glycolysis from glycogen in the muscle than in the normal situation. In some subjects the cause of fatigue may be related to a more rapid accumulation of lactate in the cold muscle, while in others fatigue may be related to alternative factors, e.g. low levels of ATP and phosphocreatine.

  • 22.
    Blomstrand, Eva
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Eva Blomstrands forskningsgrupp.
    Hassmén, Peter
    Ek, S
    Ekblom, Björn
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Björn Ekbloms forskningsgrupp.
    Newsholme, E A
    Influence of ingesting a solution of branched-chain amino acids on perceived exertion during exercise.1997Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 159, nr 1, s. 41-9Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    On two occasions, seven male endurance-trained cyclists performed exhaustive exercise on a cycle ergometer in the morning after they had performed a bout of exercise the preceding evening in an attempt to lower the muscle glycogen stores. The subjects exercised at a work rate corresponding to approximately 70% of their maximal oxygen uptake for 60 min, followed by another 20 min of maximal exercise. During exercise the subjects were given either a solution of branched-chain amino acids (BCAAs) or flavoured water (placebo). Every 10 min during exercise the subjects rated their perceived exertion and mental fatigue on two different Borg scales. During the 60 min exercise at a given work rate the subjects ratings of perceived exertion when they were given BCAAs were 7% lower, and their ratings of mental fatigue were 15% lower than when they were given placebo. In addition, the performance in the colour task of Stroops Colour Word Test performed after exercise was improved when BCAAs had been ingested during exercise, compared with the results from the placebo trial. There was no difference in the physical performance between the two trials measured as the amount of work done during the last 20 min of exercise when the subjects performed at their maximum. The plasma concentration ratio of free tryptophan/BCAAs, which increased by 45% during exercise and by 150% 5 min after exercise in the placebo trial, remained unchanged or even decreased when BCAAs were ingested.

  • 23.
    Blomstrand, Eva
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Eva Blomstrands forskningsgrupp.
    Møller, K
    Secher, N H
    Nybo, L
    Effect of carbohydrate ingestion on brain exchange of amino acids during sustained exercise in human subjects.2005Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 185, nr 3, s. 203-9Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    AIM: This study investigated the effect of prolonged exercise with and without carbohydrate intake on the brain exchange of amino acids, especially focussing on tryptophan and branched-chain amino acids (BCAA). METHODS: Five male subjects exercised for 3 h on a cycle ergometer at 200 +/- 7 W on two occasions; either supplemented with a 6% carbohydrate solution or with flavoured water (placebo). Catheters were inserted into the right internal jugular vein and the radial artery of the non-dominant arm. The brain exchange of amino acids during exercise was calculated from the arterial-jugular venous concentration difference multiplied by plasma flow. RESULTS: About 106 micromol (22 mg) of tryptophan was taken up by the brain during exercise in the placebo trial, whereas no significant uptake was observed in the carbohydrate trial. In accordance, the arterial concentration of free tryptophan increased from 12 +/- 1 to 20 +/- 2 micromol L(-1) during the placebo trial and was significantly higher compared with the glucose trial (14 +/- 1 micromol L(-1) at the end of exercise). Also, the arterial concentration of total tryptophan (free and albumin-bound) increased during the first 30 min of exercise in both trials, but returned to the basal level at 180 min of exercise. In both trials, BCAA were taken up by the brain while glutamine was released. CONCLUSION: The present data show that both tryptophan and BCAA are taken up by the brain during prolonged exercise, and we suggest that the cerebral uptake of tryptophan may relate to increased synthesis of serotonin (5-HT) in the brain.

  • 24. Brismar, Hjalmar
    et al.
    Agren, M.
    Holtback, U.
    beta-Adrenoceptor agonist sensitizes the dopamine-1 receptor in renal tubular cells2002Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 175, nr 4, s. 333-340Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The renal effects of dopamine are mainly mediated via the dopamine-1 receptor (D1 receptor). This receptor is recruited from intracellular compartments to the plasma membrane by dopamine and atrial natriuretic peptide (ANP), via adenylyl cyclase activation. We have studied whether isoproterenol, a beta -adrenoceptor (beta -AR) agonist that may interact with dopamine in the regulation of rat renal Na+, K+ -adenosine triphosphatase (ATPase) activity, can recruit D1 receptors to the plasma membrane. The spatial regulation of D1 receptors was examined using confocal microscopy techniques in LLCPK cells and the functional interaction between dopamine and isoproterenol was examined by studying their effects on Na+, K+ -ATPase activity in microdissected single proximal tubular segments from rat. Isoproterenol was found to translocate the D1 receptors from the interior of the cell towards the plasma membrane. The recruitment of dopamine 1 receptors was found to be cyclic adenosine phosphate (cAMP) dependent, while protein kinase C (PKC) activation was not involved. The functional studies on Na+, K+ -ATPase activity showed that the effect of isoproterenol was abolished by a D1-like receptor antagonist (SCH 23390), and mediated via protein kinase A (PKA) and PKC dependent pathways. The results provide an explanation for the interaction between G protein-coupled receptors. The effects of isoproterenol on Na+, K+ -ATPase activity can be explained by a heterologous recruitment of D1 receptors to the plasma membrane.

  • 25.
    Broomé, Michael
    et al.
    Umeå Universitet.
    Haney, M.
    Häggmark, S.
    Johansson, G.
    Åneman, A.
    Biber, B.
    Pressure-independent cardiac effects of angiotensin II in pigs2004Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 182, nr 2, s. 111-119Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND: Angiotensin II (Ang II) is a potent vasoconstrictor with an important role in the development of cardiovascular disease. Earlier results have shown a positive acute inotropic effect of Ang II in anaesthetized pigs together with significant vasoconstriction. This investigation was designed to study cardiac effects of Ang II, when blood pressure was maintained constant by experimental means. METHODS: Ang II (200 microg h(-1)) was infused in anaesthetized pigs (n = 10) at two different arterial blood pressures, the first determined by the effects of Ang II alone, and the second maintained at baseline blood pressure with nitroprusside. Cardiac systolic and diastolic function was evaluated by analysis of left ventricular pressure-volume relationships. RESULTS: Heart rate, end-systolic elastance (Ees) and pre-load adjusted maximal power (PWRmax EDV(-2)) increased at both blood pressure levels, although less when blood pressure was kept constant with nitroprusside. The time constant for isovolumetric relaxation (tau(1/2)) was prolonged with Ang II alone and shortened with Ang II infused together with nitroprusside. CONCLUSION: Ang II infusion in the pig has inotropic and chronotropic properties independent of arterial blood pressure levels, although the effects seem to be blunted by pharmacological actions of the nitric oxide donor nitroprusside.

  • 26. Carlson, H
    et al.
    Nilsson, Johnny
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Thorstensson, Alf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Zomlefer, M R
    Motor responses in the human trunk due to load perturbations.1981Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 111, nr 2, s. 221-3Artikkel i tidsskrift (Fagfellevurdert)
  • 27. Carlson, H
    et al.
    Thorstensson, Alf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Nilsson, Johnny
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Lumbar back muscle activity during locomotion: effects of voluntary modifications of normal trunk movements.1988Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 133, nr 3, s. 343-53Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mechanisms of adaptation of the trunk to changed mechanical conditions were studied during locomotion in man. The myoelectrical (EMG) activity in lumbar back muscles and the movements of the trunk were recorded in nine healthy subjects during walking and running on a motor-driven treadmill. Two different types of voluntary modifications of the movement pattern were used: (1) The trunk was kept in an extreme forward or backward tilted position. In both these situations the basic EMG pattern with two periods of activity per stride cycle was maintained during walking, whereas a major shift relative to the stride cycle (25% of the stride cycle duration) occurred in running with the trunk tilted backwards. The synchrony of the back muscle activation at both sides increased when locomotion was performed with the trunk tilted forwards. The relative duration of the EMG bursts was similar to normal locomotion and corresponded to 15-26% of the stride cycle duration in walking and 23-37% in running. (2) In the other type of modification the subjects were instructed to exaggerate the angular trunk movements either in the sagittal or in the frontal plane. The basic EMG pattern and phase relationships remained in most cases unchanged. One exception was running with exaggerated lateral movements, in which only one period of back muscle activity per stride cycle was observed. The relative duration of the bursts was longer in trials with exaggerated trunk movements as compared to normal locomotion. In walking and running with the trunk tilted forwards or backwards the lumbar back muscles were not always involved as prime movers of the trunk. This was in contrast to the more dynamic situations, in which the back muscle activity appeared to be directly involved in braking and reversing the exaggerated trunk movements.

  • 28.
    Carlsson, Lena
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Thornell, Lars-Eric
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Desmin-related myopathies in mice and man2001Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 171, nr 3, s. 341-8Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Desmin, the main intermediate filament (IF) protein in skeletal and heart muscle cells, is of great importance as a part of the cytoskeleton. The IFs surround and interlink myofibrils, and connect the peripheral myofibrils with the sarcolemma. In myotendinous junctions and neuromuscular junctions of skeletal muscle fibres, desmin is enriched. In the heart, desmin is increased at intercalated discs, the attachment between cardiomyocytes, and it is the main component in Purkinje fibres of the conduction system. Desmin is the first muscle-specific protein to appear during myogenesis. Nevertheless, lack of desmin, as shown from experiments with desmin knockout (K/O) mice, does not influence myogenesis or myofibrillogenesis. However, the desmin knock-out mice postnatally develop a cardiomyopathy and a muscle dystrophy in highly used skeletal muscles. In other skeletal muscles the organization of myofibrils is remarkably unaffected. Thus, the main consequence of the lack of desmin is that the muscle fibres become more susceptible to damage. The loss of membrane integrity leads to a dystrophic process, with degeneration and fibrosis. In the heart cardiac failure develops, whereas in affected skeletal muscles regenerative attempts are seen. In humans, accumulations of desmin have been a hallmark for presumptive desmin myopathies. Recent investigations have shown that some families with such a myopathy have a defect in the gene coding for alphaB-crystallin, whereas others have mutations in the desmin gene. Typical features of these patients are cardiac affections and muscle weakness. Thus, mutations in the desmin gene is pathogenic for a distinct type of muscle disorder.

  • 29. Colliander, E.B
    et al.
    Tesch, P.A
    Effects of detraining following short term resistance training on eccentric and concentric muscle strength1992Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 144, nr 1, s. 23-30Artikkel i tidsskrift (Fagfellevurdert)
  • 30. Colliander, E.B
    et al.
    Tesch, P.A
    Effects of eccentric and concentric muscle actions in resistance training1990Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 140, nr 1, s. 31-39Artikkel i tidsskrift (Fagfellevurdert)
  • 31. Colliander, E.B
    et al.
    Tesch, P.A
    Responses to eccentric and concentric resistance training in females and males1990Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 141, nr 2, s. 149-156Artikkel i tidsskrift (Fagfellevurdert)
  • 32. Crenshaw, A.G.
    et al.
    Gerdle, Björn
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Rehabiliteringsmedicin. Östergötlands Läns Landsting, Medicincentrum, Smärt- och rehabiliteringscentrum.
    Heiden, M.
    Karlsson, S.
    Fridén, J.
    Intramuscular pressure and electromyographic responses of the vastus lateralis muscle during repeated maximal isokinetic knee extensions.2000Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 170, s. 119-126Artikkel i tidsskrift (Fagfellevurdert)
  • 33. Cresswell, A G
    et al.
    Grundström, H
    Thorstensson, Alf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Observations on intra-abdominal pressure and patterns of abdominal intra-muscular activity in man.1992Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 144, nr 4, s. 409-18Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim was to investigate possible relationships between activities of the individual muscles of the ventrolateral abdominal wall and the development of pressure within the abdominal cavity. Intra-muscular activity was recorded bilaterally from transversus abdominis, obliquus internus, obliquus externus and rectus abdominis with fine-wire electrodes guided into place using real-time ultrasound. Intra-abdominal pressure was measured intragastrically using a micro tip pressure transducer. Six males were studied during loading and movement tasks with varied levels of intra-abdominal pressure. During both maximal voluntary isometric trunk flexion and extension, transversus abdominis activity and intra-abdominal pressure remained constant, while all other abdominal muscles showed a marked reduction during extension. When maximal isometric trunk flexor or extensor torques were imposed upon a maximal Valsalva manoeuvre, transversus abdominis activity and intra-abdominal pressure remained comparable within and across conditions, whereas obliquus internus, obliquus externus and rectus abdominis activities either markedly increased (flexion) or decreased (extension). Trunk twisting movements showed reciprocal patterns of activity between the left and right sides of transversus abdominis, indicating an ability for torque development. During trunk flexion--extension, transversus abdominis showed less distinguished changes of activity possibly relating to a general stabilizing function. In varied pulsed Valsalva manoeuvres, changes in peak intra-abdominal pressure were correlated with mean amplitude electromyograms of all abdominal muscles, excluding rectus abdominis. It is concluded that the co-ordinative patterns shown between the muscles of the ventrolateral abdominal wall are task specific based upon demands of movement, torque and stabilization. It appears that transversus abdominis is the abdominal muscle whose activity is most consistently related to changes in intra-abdominal pressure.

  • 34.
    Damber, Jan-Erik
    et al.
    Umeå University, Department of Physiology.
    Bergh, Anders
    Umeå University, Department of Physiology.
    Fagrell, Bengt
    Danderyds sjukhus.
    Lindahl, Olof
    Rooth, Pål
    Umeå University, Department of Histology and Cell Biology.
    Testicular microcirculation in the rat studied by videophotometric capillaroscopy, fluorescence microscopy and laser Doppler flowmetry1986Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 126, nr 3, s. 371-6Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Testicular capillary blood flow was studied in rats using laser Doppler flowmetry, in vivo fluorescence microscopy and videophotometric capillaroscopy. All the methods revealed rhythmical oscillations in testicular microcirculation with a periodicity of 4-10 c.p.m. In arterioles, capillaries and small post-capillary vessels, periods of continuous blood flow alternated with periods of no or very low flow. No visible leakage of dextran-150 was observed from the testicular blood vessels. Four, 8 and 16 h after an s.c. injection of 200 IU hCG the blood flow was continuous and there was leakage of dextran-150 from the microvessels to the interstitial tissue. Twenty-four and 32 h after hCG the blood flow pattern was again rhythmical, and at 32 h there was no leakage of dextran-150. This suggests that hCG induces changes in blood flow and transvascular fluid exchange in the testis, perhaps by altering smooth muscle activity at the arteriolar-level.

  • 35.
    Damber, Jan-Erik
    et al.
    Umeå University, Department of Physiology.
    Lindahl, Olof
    Selstam, Gunnar
    Umeå University, Department of Physiology.
    Tenland, Torsten
    Umeå University, Department of Physiology.
    Rhythmical oscillations in rat testicular microcirculation as recorded by laser Doppler flowmetry1983Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 118, nr 2, s. 117-23Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have earlier reported that local testicular blood flow, recorded by laser Doppler flowmetry, shows large oscillations with a frequency of 5-10 min-1. In the present study it is proposed that the recorded oscillations represent mainly local microvascular blood flow variations rather than variations in total testicular blood flow or tissue movements. The reasons for this are: (a) Blood flow simultaneously measured at two separate sites showed oscillations with different frequencies. (b) A local subcapsular injection of room-tempered saline under one probe site eradicated oscillations under that probe but not under another adjacent probe. (c) When the testicular capsule was split open, recordings of blood flow continued to show oscillations. (d) The amplitude of the oscillations was rather large (peak to peak value about 50% of mean flow value). No movements of the testicular surface were seen. A 20 min continuous infusion of 0.4 microgram/min noradrenaline did induce a decrease in plasma testosterone concentration, but did not change the mean blood flow. However, the oscillations nearly completely disappeared during the infusion period. The present study also shows that laser Doppler flowmetry is a versatile method and the rat testis provides a suitable organ in the study of the origin and functional importance of these oscillations

  • 36.
    Damber, Jan-Erik
    et al.
    Umeå University, Department of Physiology.
    Lindahl, Olof
    Selstam, Gunnar
    Umeå University, Department of Physiology.
    Tenland, Torsten
    Umeå University, Department of Physiology.
    Testicular blood flow measured with a laser Doppler flowmeter: acute effects of catecholamines.1982Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 115, nr 2, s. 209-15Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Laser Doppler flowmetry was used to continuously measure testicular blood flow in rats. The method was found applicable on surgically exposed testes. Regular oscillations in blood flow, with a periodicity of 8.6 +/- 0.7 cycles per minute (mean +/- SD), were observed in recordings from 22 to 23 rats. Clamping of the testicular artery reduced the blood flow signal to background values. Effects of catecholamines administered into the tail artery on testicular blood flow together with systemic effects on mean arterial blood pressure and heart rate were measured. It was found that noradrenaline as well as adrenaline caused a significant decrease in blood flow when 10 micrograms was injected. Only noradrenaline decreased the blood flow when 1 microgram was given. The large oscillations detected in the blood flow recordings disappeared quickly when 10 or 1 micrograms of both hormones was administered. It was concluded that catecholamines can exert rapid effects on testicular blood flow

  • 37. Eckberg, D
    et al.
    Wallin, G
    Fagius, J
    Lundberg, Lars
    Torebjörk, E
    Prospective study of symptoms after human microneurography1989Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 137, nr 4, s. 567-569Artikkel i tidsskrift (Fagfellevurdert)
  • 38.
    Edin, Benoni B
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    The 'initial burst' of human primary muscle spindle afferents has at least two components.1991Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 143, nr 2, s. 169-175Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ten muscle spindle primary afferents from the extensor digitorum communis muscle of man were studied with single unit afferent recordings. Responses to slow test stretches with three different pre-history conditions were assessed to investigate the contribution of rapid stretches to the stretch sensitization phenomenon. In two of the conditions, the slow test ramps were preceded by rapid stretch after which the parent muscle of the receptor was either (a) kept short for 5 seconds or (b) kept long for 3.2 seconds and then returned to the short muscle length for 5 seconds. The third condition (c) consisted of a slow stretch from short to long muscle length followed by a rapid return to the short muscle length, in turn followed by 5 seconds at the short muscle length. Afferent responses were depressed when the muscle had been kept at the long length after the rapid stretches (condition b) and enhanced when the muscle had been kept at the short length (conditions a & c). A prominent 'initial burst' was only present in the afferent discharge when the parent muscles of the primary endings had been kept short (condition a). A second, more prolonged burst was present for conditions (a) and (c) but was lacking or inconspicuous when the muscle had been kept long after rapid stretches (condition b). The rapid stretches in the stretch sensitization paradigm appear to be a primary factor not only for the enhanced responses of sensitized primary afferents but also for the depressed responses of desensitized primary afferents.

  • 39.
    Edin, Benoni B
    et al.
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    Vallbo, A B
    Twitch contraction for identification of human muscle afferents.1987Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 131, nr 1, s. 129-138Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A classical test to differentiate between Golgi tendon organs and muscle spindles is the twitch contraction elicited by electrical stimulation. The possibility of producing maximal twitches in the finger extensor muscles using surface stimulation over the muscle belly was investigated as well as the feasibility of the test in microneurography experiments. Electrical stimuli were applied either over the muscle in the forearm or the radial nerve in the upper arm, while the resulting torque output at single metacarpophalangeal joints was measured. The relationship between current intensity and maximal contraction force was determined and stimulus response plots were constructed over a large range of current intensities. Stimulation of the radial nerve always yielded plots with a steep and monotonous rising limb up to a plateau. It was concluded that the plateau represented maximal twitch contractions. With transcutaneous stimulation over the muscle belly, the stimulus response plots were usually more complex. However, this could be explained by force transmission through the intertendinous connections on the dorsum of the hand and by antagonist activation. It was concluded that maximal twitch contractions can readily be elicited in the human extensor digitorum muscle with nonpainful transcutaneous electrical stimulations. Moreover, maximal twitches are compatible with single unit recording from muscle afferents in microneurography experiments.

  • 40. Eiken, O
    et al.
    Tesch, P.A
    Effects of acute hyperoxia and hypoxia on dynamic and sustained static performance of the human quadriceps muscle1984Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 122, nr 4, s. 629-633Artikkel i tidsskrift (Fagfellevurdert)
  • 41.
    Eiken, Ola
    et al.
    Karolinska Institutet.
    Bjurstedt, H.
    Dynamic exercise in man as influenced by experimental restriction of blood flow in the working muscles1987Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 131, nr 3, s. 339-345Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects of reduced muscle perfusion pressure on dynamic exercise performance and cardiovascular and respiratory functions were investigated. Eight subjects were studied during supine cycle ergometry at stepwise increasing workloads until exhaustion with and without the legs exposed to a supra-atmospheric pressure of 50 mmHg (Leg Positive Pressure, LPP), a novel and convenient means of reducing the perfusion pressure in the working muscles. In the LPP condition exercise performance was reduced by 40% which, judging from assessments of perceived exertion, was due to premature muscle fatigue, indicating local or overall underperfusion of the working muscles. At any given work load, the arterial pressure response was considerably stronger during LPP than in the control condition. LPP also caused greater increases in blood lactate concentration and pulmonary ventilation, the differences from control increasing with the work load. Furthermore, the ventilatory equivalent for O2 at a given work load was markedly higher in the LPP than in the control condition, while exercise-induced decreases in end-tidal PCO2 were considerably exaggerated by LPP. The augmented pressor response during flow-restricted exercise, together with the strong ventilatory response which was out of proportion to overall O2 uptake, suggests increased activation of muscle chemoreflexes by accumulation of metabolic end products, the increased pressor response tending to reduce the local flow error in the working muscles.

  • 42.
    Eiken, Ola
    et al.
    Simon Fraser University.
    Convertino, V. A.
    Doerr, D. F.
    Dudley, G. A.
    Morariu, G.
    Mekjavic, I. B.
    Characteristics of the carotid baroreflex in man during normal and flow-restricted exercise1992Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 144, nr 3, s. 325-331Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Eight subjects were studied in the supine position at rest, during normal dynamic leg exercise (control exercise) and with blood-flow restriction in the working legs (flow-restricted exercise). Graded muscle blood-flow restriction was accomplished by applying a supra-atmospheric pressure of 50 mmHg to the working legs. During incremental-load exercise, flow restriction reduced exercise performance and peak heart rate by 36% and 13%, respectively. The function of the cardiac branch of the carotid baroreflex was studied over its full operational range, at rest and during constant-load control and flow-restricted exercise, by measuring R-R intervals during application of pulse-synchronous graded pressures (40 to -65 mmHg) in a neck-chamber device. Heart rate and arterial pressure were higher during flow-restricted than control exercise, indicating that the flow restriction activated the muscle chemoreflex. Raising the carotid transmural pressure (systolic arterial pressure minus neck-chamber pressure) was accompanied by increasing R-R intervals in all conditions. The set point (point of baseline carotid transmural pressure and R-R interval) coincided with the midportion of the pressure-response curve at rest and with the threshold point of the curve during exercise. The maximal rate of change in relative R-R intervals and the corresponding carotid transmural pressure range were higher during control exercise than at rest and highest during flow-restricted exercise, indicating that exercise and especially flow-restricted exercise increased carotid baroflex sensitivity, and shifted the carotid baroreflex optimal buffering range to higher pressures. The results suggest that the carotid baroflex attenuates exercise heart rate increases mediated by the muscle chemoreflex and/or by central command.

  • 43.
    Eiken, Ola
    et al.
    Swedish Defence Research Agency, Defence Medicine, Berzelius v. 13, Karolinska Institutet.
    Kölegård, Roger
    Swedish Defence Research Agency, Defence Medicine, Berzelius v. 13, Karolinska Institutet.
    Comparison of vascular distensibility in the upper and lower extremity2004Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 181, nr 3, s. 281-287Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aim: Because of the great differences in hydrostatic pressure acting along the blood vessels in the erect posture, leg vessels are exposed to greater transmural pressures than arm vessels. The in vivo pressure-distension relationship of arteries, arterioles and veins in the arm were compared with those of the leg. Methods: Experiments were performed with the subject (n = 11) positioned in a pressure chamber with an arm or lower leg (test limb) extended at heart level through a hole in the chamber door. Intravascular pressure in the arm/lower leg was increased by stepwise increasing chamber pressure to +180 and +210 mmHg, respectively. Diameters of blood vessels and arterial flow were measured using ultrasonographic/Doppler techniques. Changes in forearm and lower leg volumes were assessed using an impedance technique. The subject rated perceived pain in the test limb. Results: The brachial and radial arteries were found to be more distensible than the posterior tibial artery (P < 0.001). Likewise, the distension was more pronounced in the cephalic than in the great saphenous vein (P < 0.001). In the brachial artery, but not in the posterior tibial artery, flow increased markedly at the highest levels of distending pressure (P < 0.001). At the highest intravascular pressures, the rate of change in tissue impedance was greater in the forearm than the lower leg (P < 0.01). At any given level of markedly increased pressure, pain was rated higher in the arm than in the leg (P < 0.001). Conclusion: It seems that the wall stiffness of arteries, pre-capillary resistance vessels and veins adapts to meet the long-term demands imposed by the hydrostatic pressure acting locally on the vessel walls.

  • 44.
    Eiken, Ola
    et al.
    Karolinska Institutet.
    Lind, F.
    Bjurstedt, H.
    Effects of blood volume distribution on ventilatory variables at rest and during exercise1986Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 127, nr 4, s. 507-512Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ventilatory variables and heart rate (HR) were investigated in eight supine subjects during dynamic leg exercise at 0 and 100 W with and without the lower portion of the body exposed to a pressure of -50 mmHg (lower body negative pressure, LBNP). Resting values of inspired minute volume (V1), and respiratory drive in terms of mouth occlusion pressure (P0.1) were unchanged, whereas HR was higher during LBNP than in the control condition. Exercise values for HR in steady state were not affected by LBNP, whereas V1 was 15 and 11% lower and P0.1 was 20 and 11% lower in this condition at the 0 and 100 W workload levels, respectively. Time courses for V1 at the onset of 100 W exercise were similar with and without exposure to LBNP, indicating that the sudden increase in venous return occurring upon onset of pedalling during LBNP affords no significant stimulus in the initial development of exercise hyperpnoea. That exercise ventilation and P0.1 in steady state were reduced by LBNP suggests diminished humoral and/or locally induced chemical drive due to improved blood flow in exercising muscles resulting in reduced production of muscle metabolites or facilitation of their removal.

  • 45.
    Eiken, Ola
    et al.
    Swedish Defence Research Agency.
    Mekjavic, I. B.
    Ischaemia in working muscles potentiates the exercise-induced sweating response in man2004Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 181, nr 3, s. 305-311Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    AIM: The purpose was to examine whether graded ischaemia in the working muscles affects the rate of sweating and the control of exercise core temperature.

    METHODS: Eight subjects performed cycle ergometry exercise in the supine position with (ischaemic exercise) and without (control exercise) restriction of blood flow in the contracting muscles, accomplished by exposure of the legs to a supra-atmospheric pressure of 6.6 kPa. Each subject performed one exhaustive incremental work rate trial and one steady-state exercise trial (at 33% of control peak work rate), in both the control and ischaemia conditions.

    RESULTS: Ischaemia decreased work performance by 45% so that in this condition the steady-state work rate level corresponded to 63% of ischaemic peak work rate. Ischaemia did not affect the oesophageal temperature equilibrium in the steady-state trials, but potentiated the exercise sweating response. Exercise responses of mean arterial pressure, heart rate and pulmonary ventilation were potentiated by ischaemia.

    CONCLUSION: During ischaemic exercise sweat secretion was potentiated by non-thermal and/or local thermal stimuli.

  • 46.
    Eiken, Ola
    et al.
    Karolinska Institutet.
    Sun, J. C.
    Mekjavic, I. B.
    Effects of blood-volume distribution on the characteristics of the carotid baroreflex in humans at rest and during exercise1994Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 150, nr 1, s. 89-94Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Seven supine subjects were studied at rest and during mild to moderate dynamic leg exercise with and without unloading of the cardiopulmonary baroreceptors accomplished by exposing the lower portion of the body to a subatmospheric pressure of 20 mmHg (Lower Body Negative Pressure, LBNP). The function of the cardiac branch of the carotid baroreflex was studied over its full operational range by measuring R-R intervals during application of pulse synchronous graded pressures (40 to -65 mmHg) in a neck-chamber device. Raising the carotid transmural pressure (systolic arterial pressure minus neck-chamber pressure) induced increasing R-R intervals in all conditions. In conformity with previous results from our laboratories it was found that the maximal rate of change in relative R-R intervals and the corresponding transmural pressure were higher during exercise than at rest, indicating that exercise increased the carotid baroreflex sensitivity and shifted its optimal buffering range to higher arterial pressures. LBNP did not affect the characteristics of the reflex at rest nor during exercise. It is concluded that reduced central venous pressure with consequent selective cardiopulmonary receptor disengagement exerts no influence on the carotid baroreflex control of heart rate (HR), as tested over the entire arterial pressure-effector response relation, either at rest or during mild-moderate exercise.

  • 47.
    Eiken, Ola
    et al.
    Karolinska Institutet.
    Tesch, P.A.
    Effects of hyperoxia and hypoxia on dynamic and sustained static performance of the human quadriceps muscle1984Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 122, nr 4, s. 629-633Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of variations in inspired PO2 on dynamic and static muscle performance of the left quadriceps muscle was studied. Eight subjects performed (1) 60 maximal consecutive dynamic contractions and (2) one sustained exhaustive static contraction at 27% of maximal voluntary contraction (MVC). Breathing mixtures containing 11%, 21% or 99% O2, were administered. Peak torque as an average of the 60 knee extensions was higher (p less than 0.01) during hyperoxia (mean +/- SE = 104 +/- 4 Nm) than during normoxia (98 +/- 4 Nm), but did not differ significantly between hypoxia (95 +/- 5 Nm) and normoxia. Peak torque of individual extensions declined more rapidly during hypoxia than during normoxia, differing in the final 12 extensions by 11% from normoxic values. Static endurance time was reduced (p less than 0.02) during hypoxia (152 +/- 12 s) as compared to normoxia (189 +/- 13 s) and hyperoxia (169 +/- 11 s). No significant difference in endurance time was demonstrated between hyperoxia and normoxia. Thus, hypoxia impaired muscle performance in both dynamic and sustained static exercise, whereas acute hyperoxia improved dynamic but not static muscle performance. The results are interpreted in terms of differences in rate of intramuscular H+ accumulation.

  • 48. Erga, KS
    et al.
    Peen, E
    Eneström, S
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för molekylär och klinisk medicin, Molekylär och immunologisk patologi. Östergötlands Läns Landsting, Laboratoriemedicinskt centrum, Klinisk patologi och klinisk genetik.
    Reed, RK
    Effects of lactoferrin on rat dermal interstitial fluid pressure (Pif) and in vitro endothelial barrier function2001Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 171, nr 4, s. 419-425Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We recently demonstrated that intravenous (i.v.) injection of the iron-binding protein lactoferrin (Lf) followed by antilactoferrin (aLf) antibodies or iron-saturated Lf alone increased albumin extravasation in vivo in several tissues including skin. Increased driving pressure for blood-tissue exchange or direct effects of Lf on the endothelial barrier are possible mechanisms. We therefore, firstly, measured interstitial fluid pressure (Pif) in dermis of rats given 1 mg Lf i.v. followed 30 min later by aLf or saline and circulatory arrest 1 or 5 min thereafter and compared with controls. Secondly, transmonolayer passage of Evans blue labelled albumin (EB-albumin) was evaluated in porcine pulmonary artery endothelial cells exposed to iron-free or iron-saturated Lf (both 100 ╡g mL-1) in the absence and presence of 0.5 mM hydrogen peroxide. Pif increased significantly at 11-30 min following Lf to +2.1 ▒ 0.3 and +1.7 ▒ 0.2 mmHg at 11-20 and 21-30 min, respectively, compared with +0.1 ▒ 0.2 mmHg before Lf (P < 0.05, n = 25). Endothelial transmonolayer passage of EB-albumin during 3 h was not affected by iron-free or iron-saturated Lf neither in the absence nor presence of hydrogen peroxide that increased passage 3.5 times compared with controls. In conclusion, Lf-induced increase in albumin extravasation in rat skin is not explained by changes in Pif (because Lf raised Pif significantly) or direct effects of Lf on the endothelial barrier.

  • 49.
    Eriksson, S
    et al.
    Department of Physiology, Karolinska Institute, Stockholm, Sweden.
    Andersson, B
    Gunnarsson, Ulf
    Department of Physiology, Karolinska Institute, Stockholm, Sweden.
    Rundgren, M
    Hypertension and thirst outlasting renal vasoconstriction as effects of a brief evaluation of systemic angiotensin II in sheep.1994Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 150, nr 2, s. 181-8Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of 10 min intracarotid (i.c.) and intravenous (i.v.) infusions of angiotensin II (Ang II; 20 pmol kg-1 min-1) on carotid blood pressure (cBP) and renal blood flow (RBF) was studied in unanaesthetized ewes without and with pre-treatment with the alpha 1- and beta-adrenoceptor blocker labetalol. RBF was also monitored during 30 min intracerebroventricular (ICV) infusions of Ang II at 2 pmol kg-1 min-1. The i.c. infusions of Ang II induced about 50 mmHg rise in cBP. A steep decline occurred during 5 min post-infusion, followed by a much slower reduction with the cBP remaining above control level at 40 min post-infusion. The pressure elevation induced by i.v. Ang II was less pronounced but exhibited a similar pattern. Labetalol significantly reduced the pressor response to i.c. as well as i.v. Ang II. The i.c. and i.v. infusions of Ang II conspicuously reduced the RBF regardless of whether the ewes were labetalol-treated or not. At 5 min after the infusions RBF had returned to control level. The ICV infusions did not influence the RBF. Ang II i.c. elicited thirst in 50% of the ewes with the urge to drink remaining at 40 min post-infusion. The dipsogenic response was not reduced by labetalol pretreatment. The results imply that no cerebral component contributes to the reduction in RBF induced by systemic Ang II. However, a centrally mediated action seems to be the cause of the long-lasting post-infusion cBP elevation and dipsogenic response.(ABSTRACT TRUNCATED AT 250 WORDS)

  • 50. Esbjörnsson, M
    et al.
    Jansson, E
    Sundberg, C J
    Sylvén, C
    Eiken, Ola
    Karolinska Institutet.
    Nygren, A
    Kaijser, L
    Muscle fibre types and enzyme activities after training with local leg ischaemia in man.1993Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 148, nr 3, s. 233-41Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Eight healthy men performed supine one-legged training on a bicycle ergometer 45 min per leg four times per week for 4 week. The ergometer and lower body were inside a pressure chamber, the opening of which was sealed at the level of the crotch. One leg trained with impeded leg blood flow (I-leg), induced by an increased (50 mmHg) chamber pressure, at the highest tolerable intensity. The contralateral leg trained at the same power under normal pressure (N-leg). Before and after training biopsies were taken from the vastus lateralis of both legs and maximal one-legged exercise tests were executed with both legs. Biopsies were repeated when the subjects had been back to their habitual physical activity for 3 months. Training increased exercise time to exhaustion, but more in the I-leg than in the N-leg. After training, the I-leg had higher activity of citrate synthase (CS), a marker of oxidative capacity, and lower activity of the M-subunit of lactate dehydrogenase isoenzymes. It also had a higher percentage of type-I fibres and a lower percentage of IIB fibres, larger areas of all fibre types and a greater number of capillaries per fibre. It is concluded that ischaemic training changes the muscle metabolic profile in a direction facilitating aerobic metabolism. An altered fibre-type composition may contribute, but is not enough prerequisite for the change.

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