Role of various vasodepressor systems in the acute hypotensive effect of captopril in man.

The acute hypotensive effect of captopril 25 mg was investigated in 26 hypertensive patients (11 with essential and 15 with renal arterial disease). Intra-arterial blood pressure was recorded continuously and arterial blood was sampled for renin, angiotensin I and II, aldosterone, kininase II, catecholamines and prostaglandins. Captopril led to an increase in plasma renin activity, active and total plasma renin concentration and angiotensin I, a decrease in plasma kininase II activity, angiotensin II, aldosterone, prostaglandins E2 and F2 alpha and no change in plasma (nor) adrenaline, dopamine and inactive renin concentration. The hypotensive effect of captopril was related to the changes in plasma angiotensin II level and inversely to the changes in prostaglandin E2; the correlation coefficients were low, respectively 0.61 and -0.44. It is likely that the acute hypotensive effect of captopril to some extent is related to changes in plasma angiotensin II and in prostaglandins E2 and F2 alpha. There is no evidence for a role of the adrenergic systems in the hypotensive response.