EFFECTS OF EXERCISE ON BLOOD PRESSURE, SYMPATHETIC NERVE ACTIVITY, AND MUSCLE BLOOD FLOW RESPONSES TO HYPERINSULINEMIA IN MEN.

Abstract

1212 To test the effects of a single bout of exercise on blood pressure (BP), sympathetic nerve activity (SNA), and forearm blood flow (FBF) responses to hyperinsulinemia, 10 healthy men were submitted, in a random order, to two hyperinsulinemic euglycemic clamps performed after 45 min of bicycle exercise(50%VO2max) or seated rest. Basal and peak responses of BP, heart rate(HR), SNA (microneurography), FBF (plethysmography), and forearm vascular resistance (FVR) were studied. Insulin infusion significantly increased systolic blood pressure (Basal=127±10 vs. Peak=132±9 mmHg, P<0.05), but caused no change in mean and diastolic blood pressures. Exercise significantly decreased mean BP (Exercise Day=90±9 vs. Rest Day=93±7 mmHg, P<0.05). Exercise significantly increased basal HR(Exercise Day=62±10 vs. Rest Day=58±7 bpm, P<0.05), and insulin infusion significantly increased HR at Rest Day (Basal=58±7 vs. Peak=62±5 bpm, P<0.05), but not at Exercise Day (Basal=62±10 vs. Peak=61±6 bpm). Insulin infusion significantly increased SNA(Basal=18±5 vs. Peak=33±9 burst/min, P<0.05), and exercise did not change this response. Insulin infusion did not modify FBF, but it was significantly increased by exercise (Exercise Day=2.14±0.69 vs. Rest Day=1.72±0.52 ml/min/100ml, P<0.05). FVR was lower in Exercise than in Rest Day (46±17 vs. 60±24 units, P<0.05). In both days, insulin infusion significantly decreased FVR (Basal=57±25 vs. Peak=49±16 units, P<0.05). Conclusions: 1) Exercise increases FBF, and reduces FVR and MBP; 2) Insulin infusion increases SNA and systolic BP and; 3) Exercise modifies HR responses to hyperinsulinemia, but does not change BP, SNA, FBF, and FVR responses during hyperinsulinemic euglycemic clamp.