Increase in systolic blood pressure and catecholamine level during hyperinsulinemia in a placebo-controlled euglycemic clamp in healthy subjects

Abstract

Hyperinsulinemia has been shown to induce vasodilation and activation of the sympathetic nervous system. Whether these effects result in changes in blood pressure (BP) is discussed controversially. We measured BP and catecholamine levels in 50 healthy subjects during a 40-min baseline phase and during a 100-min euglycemic clamp phase. In a double-blind, between-subject comparison, 30 subjects were infused with 1.5mU insulin/kg x min, 20subjects were infused with saline solution. Insulin levels increased during insulin infusion from (mean+/-SE) 23.7 0.6 pmol/l to 406.2+/-3.0 pmol/l, but remained unchanged during placebo infusion. Blood glucose levels were identical during both conditions. Systolic BP increased from 116.6+/-1.5 mmHg to 119.8+/-1.8 mmHg during insulin infusion and decreased from 116.6+/-2.3 mmHg to 114.0+/-2.4 mmHg during placebo infusion (p<0.001, for the difference between the effects of insulin vs. placebo). Heart rate was higher during insulin infusion as compared to placebo infusion (63.8+/-1.9 vs. 60.9+/-2.4 beats/min, p<0.05). Norepinephrine levels increased from 1.25+/-0.09 to 1.58+/-0.12 nmol/l during insulin infusion and remained unchanged during placebo infusion (1.24+/-0.09 vs. 1.29+/-0.11 pmol/l; p<0.001). Epinephrine levels were also higher during insulin as compared to placebo infusion (249.8+/-17.4 vs. 212.8+/-21.1 pmol/l, p<0.001). The changes did not depend on whether the subject experienced his first or second clamp. Data demonstrate reproducable increasing effects of hyperinsulinemia within the normal physiological range on catecholamine release and systolic BP in healthy humans.