Effect of Resistance Training on Microvascular Density and eNOS Content in Skeletal Muscle of Sedentary Men

Abstract

The effects of resistance training (RT) on muscle mass, strength and insulin sensitivity are well established, but the underlying mechanisms are only partially understood. The main aim of this study is to investigate whether RT induces changes in endothelial enzymes of the muscle microvasculature, which would increase NO bioavailability and could contribute to improved insulin sensitivity. Eight previously sedentary males (age 20±0.4y, BMI 24.5±0.9 kg.m-2) completed 6wk of RT 3x/week. Muscle biopsies were taken from the m. vastus lateralis and microvascular density and endothelial specific eNOS content, eNOS Ser1177 phosphorylation and NOX2 content were assessed pre- and post-RT using quantitative immunofluorescence microscopy. Whole body insulin sensitivity (measured as Matsuda Index), microvascular filtration capacity (functional measure of the total available endothelial surface area) and arterial stiffness (augmentation index, central and peripheral pulse wave velocity) were also measured. Measures of microvascular density, microvascular filtration capacity, microvascular eNOS content, basal eNOS phosphorylation and endothelial NOX2 content did not change from pre-RT to post-RT. RT increased insulin sensitivity (P <0.05) and reduced resting blood pressure and augmentation index (P <0.05), but did not change central or peripheral pulse wave velocity. In conclusion RT did not change any measure of muscle microvascular structure or function