Effect of angiotensin-converting enzyme inhibition by captopril on cardiac output, coronary blood flow, and systemic arterial blood pressure in the intact and in the bilaterally nephrectomized rabbit.

Abstract

The purpose of this study was to investigate the hemodynamic responses, mainly cardiac output and regional blood flow, to converting enzyme inhibition by captopril in the intact and nephrectomized rabbit. Twenty-one New Zealand white rabbits anesthetized with pentobarbital has systemic arterial blood pressures measured and cardiac output and regional blood flow determined by the microsphere method. Captopril (1--3 mg/kg) significantly reduced cardiac output in the intact but not in nephrectomized rabbits. In both the intact and nephrectomized animals, captopril was associated with small but not significant decreases in blood pressure and no significant change in total peripheral vascular resistance or heart rate. Regional blood flow was reduced, but the fractional distribution of cardiac output to the myocardial, lung (bronchial), hepatic, and splanchnic (small intestine) circulations was unchanged after captopril. These data suggest that the reduction in cardiac output induced by converting enzyme inhibition may be attributed to a fall in venous return that in turn may be dependent on renal factors.