Postexercise responses of muscle sympathetic nerve activity and blood flowto hyperinsulinemia in humans

Although insulin and exercise cause dramatic changes in physiological param eters, the impact of exercise on neural and hemodynamic responses to insuli n administration has not been described. In a study of the effects of a sin gle bout of exercise on blood pressure (BP), muscle sympathetic nerve activ ity (MSNA), and forearm blood flow (FBF) responses to insulin infusion duri ng the postexercise period, 11 healthy men underwent, in a random order, tw o hyperinsulinemic euglycemic clamps performed after 45 min of 1) bicycle e xercise (50% peak O-2 uptake, Exercise session) and 2) seated rest (Control session). Data were analyzed during baseline and steady-state periods. Alt hough insulin levels and insulin sensitivity were similar, baseline plasma glucose levels were significantly lower in the Exercise than in the Control session. Mean BP was significantly lower (3%) and FBF was higher (27%) in the Exercise session. Exercise increased insulin-induced MSNA enhancement ( 84%) without; changing FBF and BP responses to hyperinsulinemia. In conclus ion, a single bout of exercise that does not alter insulin sensitivity exac erbates insulin-induced increase in MSNA without changing FBF and BP respon ses to hyperinsulinemia.