Angiotensin converting enzyme inhibitors. Disparities in the mechanism of their antihypertensive effect.

Systemic and renal hemodynamics were studied by invasive and noninvasive techniques in 30 patients with mild to moderate essential hypertension before and after antihypertensive therapy with captopril (12 patients), enalapril (8 patients), and lisinopril (10 patients). All three angiotensin-converting enzyme (ACE) inhibitors reduced arterial pressure to about the same extent: captopril by 14%, enalapril by 18%, and lisinopril by 13%. However, lisinopril produced a significant fall (14%, P less than 0.001) in cardiac output that was not seen with captopril or enalapril therapy. Moreover, lisinopril elicited an increase in renal blood flow (22%, P less than 0.05) that was more marked than that with enalapril (12%) or captopril (4%). Although left ventricular mass was reduced (P less than 0.05) with all three agents, enalapril induced a twofold greater reduction (29%) than captopril (14%) or lisinopril (12%). These findings suggest that systemic and renal hemodynamic effects may be drug specific and not uniform for all ACE inhibitors.