Effect of angiotensin converting enzyme inhibition on plasma endothelin in congestive heart failure

The influence of angiotensin converting enzyme inhibitor therapy on elevated plasma endothelin concentrations in chronic heart failure was investigated by measuring plasma endothelin immunoreactivity in 22 patients with severe but stable chronic heart failure before and after 16 weeks of therapy with quinapril (n = 12) or captopril (n = 10). Plasma endothelin immunoreactivity in the patients (10.2 +/- 34 pg/ml) was significantly higher than a control group (5.9 +/- 1.8 pg/ml). Quinapril improved symptoms and haemodynamics but did not affect plasma endothelin immunoreactivity (11.9 +/- 2.9 pg/ml at baseline and 12.3 +/- 3.4 pg/ml after 16 weeks of quinapril). Captopril also had no effect on endothelin levels (8.1 +/- 2.9 at baseline and 8.1 +/- 3.8 pg/ml after 16 weeks of captopril). The vasodilatory effects of angiotensin converting enzyme inhibitors in heart failure are not mediated by, or associated with, changes in plasma endothelin immunoreactivity.