Effects of angiotensin I converting enzyme inhibitors on the renal excretory function, hemodynamics and renin release in isolated perfused rat kidney.

Direct renal effects of angiotensin I converting enzyme inhibitors (CEIs), captopril, SA446 and MK421, were examined in isolated rat kidneys perfused with a renin-substrate-free medium. Among three CEIs, only captopril induced a significant natriuresis, whereas SA446 and MK421 did not. UKV, renal vascular resistance and creatinine clearance were not affected by any of these CEIs. Renin release from perfused rat kidneys were not influenced by CEIs under the present experimental conditions. These results suggest that among three different types of CEIs, only captopril possesses natriuretic action in the isolated perfused rat kidney and that this action may be independent of its inhibitory action on angiotensin converting enzyme. It is also suggested that these three CEIs themselves do not have a direct effect on the renal vascular bed.