Effect of the angiotensin-converting enzyme inhibitor alacepril on ventricular function and beta-adrenoceptor number in rabbits with aortic regurgitation.

Abstract

This study was performed to determine the effects of the angiotensin-converting enzyme inhibitor alacepril on hemodynamic variables and beta-adrenoceptor number in rabbits with heart failure induced by aortic regurgitation. Aortic regurgitation was induced by perforation of the aortic valve in 12 rabbits. Sixty mg/kg of alacepril was administered by gastric tube for 7 days after manifestation of aortic regurgitation to 6 rabbits (group AR + A). The other 6 rabbits with aortic regurgitation were administered vehicle in the same fashion (group AR + C). Seven rabbits underwent sham operation (group S). One week after induction of aortic regurgitation left ventricular end-diastolic pressure was higher and cardiac output was lower in AR + C than in S. End-diastolic and end-systolic left ventricular diameter were larger and left ventricular weight was also higher in AR + C than in S. For each of these parameters, the opposite findings were obtained from a comparison of AR + A and S. Myocardial beta-adrenoceptor density and norepinephrine content were reduced in AR + C, but were restored in AR + A. These findings indicate that alacepril has beneficial effects on ventricular remodeling and function, and on sympatho-neuronal regulation in the volume-overloaded myocardium.