Evaluation of the chronotropic property of captopril in hypertensive patients.

Captopril was administered (50 mg orally) to 88 untreated hypertensive patients (70 with essential hypertension, eight with renal arterial disease, 10 with renal parenchymal disease) and to 25 hypertensive patients treated with sympatholytic or beta-blocking agent (20 with essential hypertension, five with renal arterial disease). In the former group, captopril caused a decrease in heart rate (HR) in 18 patients and an increase in only two. As a whole, captopril caused significant decreases in blood pressure without increase in HR. Significant negative correlation was observed between change in HR and plasma renin activity obtained before captopril administration (n = 79, r = -0.425, p less than 0.0001). Hypotensive and chronotropic effects of captopril were almost identical in untreated and treated patients. Hypotensive effects caused by captopril and nifedipine (20 mg orally) were almost identical. Nifedipine caused reflex tachycardia, while captopril caused slight bradycardia. Absence of compensatory tachycardia appears to be related to reduction of endogenous angiotensin II by captopril.U