Effects of exercise and insulin on insulin signaling proteins in human skeletal muscle

Publisher Website
Google Scholar
Abstract
Effects of exercise and insulin on insulin signaling proteins in human skeletal muscle. Med. Sci. Sports Exerc., Vol. 31, No. 7, pp. 998-1004, 1999. Insulin and exercise independently increase glucose metabolism in muscle. Moreover, exercise training or a prior bout of exercise increases insulin-stimulated glucose uptake in resting skeletal muscle. The present study was undertaken to compare how physiological hyperinsulinemia and moderate intensity aerobic exercise affect the tyrosine phosphorylation state and activity of insulin signaling molecules in healthy, physically inactive volunteers. Subjects had biopsies of the vastus lateralis muscle before and immediately after 30 min of either hyperinsulinemia (euglycemic insulin clamp) or moderate-intensity exercise on a cycle ergometer (∼60% of O2max). Insulin receptor and IRS-1 tyrosine phosphorylation, association of the p85 regulatory subunit of PI 3-kinase with IRS-1, IRS-1 associated PI 3-kinase activity, and glycogen synthase activity were determined in muscle biopsy specimens taken from healthy subjects before and after insulin or exercise. Physiological hyperinsulinemia increased the rate of glucose disposal from 11.4 ± 1.5 to 25.6 ± 6.7 μmol·kg−1·min−1 (P P