The Hemodynamic Response to Chronic Hyperinsulinemia in Conscious Dogs

This study describes the hemodynamic effects of chronic hyperinsulinemia in seven normal dogs. Insulin infused at 1 mU/kg/min together with glucose at 14 mg/kg/min for 7 days increased fasting plasma insulin concentration approximately six-fold. Plasma glucose concentration was unchanged on day 1 but was below control on day 6. Mean arterial pressure decreased from 81 +/- 4 mm Hg to 70 +/- 3 mm Hg, while cardiac output increased to 30 +/- 8% above control by day 7. Total peripheral resistance decreased to 69 +/- 5% of control. Urinary sodium excretion was significantly decreased and was accompanied by a 22% increase in extracellular fluid volume with no change in blood volume. All parameters returned to control levels during the recovery period. These data suggest that, in addition to promoting renal sodium retention, insulin may lower blood pressure and increase cardiac output through a peripheral vasodilatory effect.