Chronic Hyperinsulinemia Augments

Abstract To evaluate the effect of chronic hyperinsulinemia on blood pressure in salt-dependent hypertension, we infused insulin (1.0 IU/d, n=15) or saline (n=13) for 4 weeks into deoxycorticosterone acetate-salt hypertensive rats. The insu-lin infusion increased plasma insulin levels to 24±2 /i.U/mL, which was higher than in the saline-infused rats (9±1 jtU/mL) but was still within the physiological range. Blood pressure was measured by the tail-cuff method twice a week, and daily sodium intake and urinary sodium excretion were calculated for 3 weeks. At week 4, arterial pressor responsiveness to norepinephrine, angiotensin II, and hexamethonium bromide was evaluated. After 14 days of chronic infusion, the insulin group showed a higher blood pressure than the saline group (on 21st day: 178±6 versus 156±5 mm Hg, P<.05 by tail-cuff method; 171 ±4 versus 149±3 mm Hg, P<.05 by direct intra