Insulin-mediated changes in leg blood flow are coupled to capillary density in skeletal muscle in healthy 70-year-old men.
The aim of this study was to investigate to what degree the capillarization in the skeletal muscle explains the leg blood flow (LBF) changes during hyperinsulinaemia. Fifteen normotensive men from a population-based cohort of 70-year-old men in Uppsala, Sweden, were investigated. Their metabolic status (oral glucose tolerance test and euglycemic, hyperinsulinaemic clamp test results), serum lipid profile, muscle fiber distribution (myosin adenosine triphosphatase staining), and capillary supply (amylase-periodic acid-Schiff method) was evaluated. Doppler ultrasound was used before and after the clamp test to detect insulin-induced changes in LBF. Physiologic hyperinsulinemia (serum insulin, 107 mU/L) caused a moderate increase in LBF (15% +/- 11%; P =.07). Change in LBF was closely related to capillary density (r =.66; P <.01) independent of obesity, smoking and level of physical activity. An association was observed between LBF and serum free fatty acid (FFA) concentrations (r = -.57; P <.05). In multiple regression analysis, capillary density and serum FFA level together explained 71% of the variation in insulin-mediated LBF changes. Capillary rarefaction and elevated serum FFA values were associated with a vasoconstrictive effect of insulin. In conclusion, capillarization in skeletal muscle and serum FFA concentration seem to be determinants of endothelial function.
Hedman
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A
Department of Public Health and Caring Sciences/Section of Geriatrics, Uppsala University, Uppsala, Sweden.
Andersson
P E
PE
Reneland
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R
Lithell
H O
HO
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000368:Aged; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology; D002196:Capillaries / Q000000981:diagnostic imaging / Q000502:physiology*; D002452:Cell Count; D015331:Cohort Studies; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005263:Femoral Artery / Q000000981:diagnostic imaging / Q000502:physiology; D015309:Glucose Clamp Technique; D005951:Glucose Tolerance Test; D006801:Humans; D006946:Hyperinsulinism / Q000097:blood / Q000139:chemically induced; D007328:Insulin / Q000378:metabolism* / Q000494:pharmacology; D007866:Leg / Q000098:blood supply* / Q000000981:diagnostic imaging; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000502:physiology; D012016:Reference Values; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology*; D013548:Sweden; D018608:Ultrasonography, Doppler
D005230:Fatty Acids, Nonesterified; D007328:Insulin; D000251:Adenosine Triphosphatases