Effects of two structurally different angiotensin-converting enzyme inhibitors, captopril and quinapril (CI-906), in rats with one-kidney deoxycorticosterone-salt hypertension.

Possible non-renin antihypertensive actions of two angiotensin-converting enzyme inhibitors, the sulfhydryl compound captopril and the new nonsulfhydryl inhibitor quinapril (CI-906), were compared in rats with one-kidney deoxycorticosterone-salt hypertension. Plasma renin activity remained low during the 12-day treatments and showed very strong suppression of the renin-angiotensin system. Quinapril did not influence the rapidly increasing blood pressure. Although captopril tended to reduce the development of hypertension (p = 0.08), it did not have any significant effect, either. The results indicate that these ACE inhibitors with different chemical structures lack any significant blood pressure lowering mechanism in severe deoxycorticosterone-salt hypertension, a model in which they cannot act through their established antihypertensive mechanism, the inhibition of the renin-angiotensin system.