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- Hagstrom-Toft, E, et al.
(författare)
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Marked heterogeneity of human skeletal muscle lipolysis at rest
- 2002
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 51:12, s. 3376-3383
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Tidskriftsartikel (refereegranskat)abstract
- In this study, variations in lipolysis among different muscle groups were examined by measuring local net glycerol release in vivo in healthy, normal-weight subjects (n = 11) during rested, postabsorptive conditions. Microdialysis of the gastrocnemius, deltoid, and vastus lateralis muscle regions revealed that extracellular glycerol concentrations of these three muscle regions were 84.7 ± 6.7, 59.7 + 7.3, and 56.4 ± 7.5 μmol/l, respectively, and the arterial plasma glycerol concentration was 44.8 ± 2.3 μmol/l (P = 0.0003–0.006, gastrocnemius vs. others). Local tissue blood flow, as measured by Xe clearance, did not differ among the regions. Net glycerol release was significantly higher in gastrocnemius muscle than in the two other regions. There were no regional differences in glycerol uptake when studied during glycerol infusion. Gastrocnemius muscle showed a dominance of type 1 fibers (70%), whereas the vastus lateralis muscle had equal distribution of fiber types (P = 0.02). No differences in intramuscular triaclyceride content, perimuscular fat, or the adipocyte-specific protein perilipin were observed among the muscle regions. Triglyceride turnover in the gastrocnemius muscle was 3.3 + 1.4% over 24 h, which is about 10 times more rapid than the turnover rate in subcutaneous adipose tissue (P < 0.01). Thus there were marked differences in lipolytic activity among skeletal muscle groups at rest, possibly reflecting variations in fiber type.
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- Hamrin, Kerstin, et al.
(författare)
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Prolonged Exercise-Induced Stimulation of Skeletal Muscle Glucose Uptake Is due to Sustained Increases in Tissue Perfusion and Fractional Glucose Extraction
- 2011
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 96:4, s. 1085-1092
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Tidskriftsartikel (refereegranskat)abstract
- Context: The mechanisms behind the positive effects of physical activity on glucose metabolism in skeletal muscle and the time course of the effects need to be more elucidated. Objective: The aim was to examine the prolonged effects of an acute bout of one-legged exercise on local skeletal muscle glucose utilization and tissue perfusion. Design and Setting: Interstitial glucose concentration, local tissue perfusion, glucose uptake, and effects of insulin infusion were studied 12 h after an acute bout of exercise and without prior exercise. Participants: Ten healthy subjects, five women and five men, participated in the study. Intervention: Microdialysis measurements, (133)Xe clearance, and a 2-h hyperinsulinemic euglycemic clamp were performed on two occasions. Main Outcome Measures: We measured interstitial glucose concentration and tissue perfusion in the quadriceps femoris muscle of both legs. Results: Tissue perfusion (3.3 +/- 0.6 ml x 100 g(-1) x min(-1) vs. 1.4 +/- 0.2 ml x 100 g(-1) x min(-1); P = 0.007) and basal glucose uptake (2.3 +/- 0.5 mu mol x 100 g(-1) x min(-1) vs. 0.9 +/- 0.2 mu mol x 100 g(-1) x min(-1); P = 0.006) were increased in the leg that had exercised compared to the resting leg; the findings in the resting leg were comparable to those in the control experiment without prior exercise. The relative effect of insulin on fractional skeletal muscle glucose uptake was the same in all experimental settings, and insulin did not affect tissue perfusion. Conclusions: The prolonged stimulatory effect of physical exercise on skeletal muscle glucose uptake was mediated via vascular effects combined with an increase in basal glucose transport independent of enhancement of insulin responses.
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- Qvisth, V, et al.
(författare)
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Lactate release from adipose tissue and skeletal muscle in vivo: defective insulin regulation in insulin-resistant obese women
- 2007
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Ingår i: American journal of physiology. Endocrinology and metabolism. - : American Physiological Society. - 0193-1849 .- 1522-1555. ; 292:3, s. E709-E714
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Tidskriftsartikel (refereegranskat)abstract
- To study the local tissue lactate production in the normal state and its possible disturbances in insulin resistance, rates of lactate release from adipose tissue (AT) and skeletal muscle (SM) were compared postabsorptively and during a hyperinsulinemic euglycemic clamp in 11 healthy nonobese and 11 insulin-resistant obese women. A combination of microdialysis, to measure interstitial lactate, and the 133Xe clearance technique, to determine local blood flow, were used. In the controls, local blood flow increased by 40% in SM ( P < 0.05) and remained unchanged in AT, whereas the interstitial-plasma difference in lactate doubled in AT ( P < 0.005) and was unaffected in SM during hyperinsulinemia. In the obese, blood flow and interstitial-plasma difference in lactate remained unchanged in both tissues during hyperinsulinemia. The lactate release (μmol100 g−1min−1) was 1.17 ± 0.22 in SM and 0.43 ± 0.11 in AT among the controls ( P < 0.01) and 0.86 ± 0.23 in SM and 0.83 ± 0.25 in AT among the obese women in the postabsorptive state. During insulin infusion, lactate release in the controls increased to 1.92 ± 0.26 in SM ( P < 0.005) and to 1.14 ± 0.22 in AT ( P < 0.005) but remained unchanged in the obese women. It is concluded that AT and SM are both significant sources of lactate release postabsorptively, and AT is at least as responsive to insulin as SM. The ability to increase lactate release in response to insulin is impaired in AT and SM in insulin-resistant obese women, involving defective insulin regulation of both tissue lactate metabolism and local blood flow.
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