Effects of high doses of insulin on regional blood flows during acute left ventricular failure in dogs.

Abstract

This study describes the effects of high doses of insulin on systemic haemodynamics and regional blood flows during acute ischaemic heart failure in dogs. Left ventricular (LV) dysfunction was induced by embolization of the left main coronary artery, and was evidenced by a significant increase in LV end-diastolic pressure and decrease in LVdP/dtmax and cardiac output. Measurements of femoral, renal, mesenteric and carotid blood flows showed a redistribution of cardiac output during failure. Femoral blood flow decreased to a greater extent than cardiac output, but carotid blood flow decreased in proportion to cardiac output, while mesenteric and renal blood flows were moderately reduced in relation to the decrease in cardiac output. Administration of 300 IU of fast-acting insulin significantly improved the performance of the failing left ventricle. Cardiac output was raised to levels observed before failure. The greatest increases in peripheral flow occurred in the femoral and carotid vascular beds, while the least occurred in the mesenteric and renal vascular beds. These observations indicate that insulin at high dose levels significantly improves peripheral circulation by positive inotropic and vasodilatating effects. There was a tendency to favour femoral and carotid vascular flows, but not at the expense of renal and visceral flows. Beta receptor blockade blocked neither the systemic nor regional haemodynamic effects of insulin.