Non-Corresponding Effects of an Angiotensin- Converting Enzyme Inhibitor on Cardiac and Vascular Hypertrophy in Spontaneously Hypertensive Rats

Angiotensin-converting enzyme inhibitors (ACEIs) may have different effects on cardiac hypertrophy than on vascular hypertrophy. Arginine vasopressin (AVP) may promote cardiac hypertrophy. Our aims were (1) to simultaneously examine the chronic effects of ACEIs on hypertrophy of the heart and hypertrophy of the coronary and renal interlobular arteries, and (2) to clarify the relation between AVP concentration (AVPC) and cardiac hypertrophy. ACEI (delapril: 30mg/kg/day) or vehicle (5% arabic gum) was administered in a preventive (4 to 28 weeks of age) or a therapeutic (12-24 weeks of age) protocol in spontaneously hypertensive rats. In both protocols, delapril produced a slight but significant decrease in systolic blood pressure. In the therapeutic protocol, the weight of the left ventricle (mean±SE) was lower (p<0.05) in the ACEI group (64±2mg/100g body weight) than in the control group (69±1mg/100g body weight). Plasma renin activity was significantly higher in the ACEI group than in the control group in both the preventive (p <0.01) and therapeutic (p<0.01) protocols. In the therapeutic protocol, AVPC was significantly (p<0.05) lower in the ACEI group than in the control group. AVPC was significantly (p=0.02, r=0.46) correlated with the weight of the left ventricle in the therapeutic protocol. For both protocols, no differences were noted between the ACEI and control groups in the vascular hypertrophy of the coronary and renal interlobular arteries. We conclude that (1) the preventive or therapeutic effect of ACEIs on hypertrophy may not be the same in the heart as in the coronary and renal arteries; and (2) AVP was significantly correlated with the left ventricular weight. This indicates that AVP could play a role in the etiology of cardiac hypertrophy in SHR. (Hypertens Res 2000; 23: 483-490)