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 six­fold. 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 accom­ panied 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.