Renal response to converting enzyme blockade
De Leeuw, P.W.; van Es, P.N.; Looman, M.; Birkenhäger, W.H.
Journal of Hypertension. Suppl Official Journal of the International Society of Hypertension 3(3): S295-S296
1985
ISSN/ISBN: 0952-1178 PMID: 2856823 Document Number: 249058
To investigate the renal actions of the converting enzyme inhibitor enalaprilic acid, incremental doses of this drug were infused into the renal artery of hypertensive patients just before renal angiography. One group (n = 6) received doses of 0.1, 0.3 and 1 microgram/kg per min, while in another group (n = 7) doses of 1, 3 and 10 micrograms/kg per min were given. Each dose was infused for 10 min, at the end of which renal blood flow was assessed by means of xenon-washout. At the same time, blood was sampled from the renal artery and vein for determination of converting enzyme, renin and angiotensin II. Enalaprilic acid caused a dose-related suppression of converting enzyme activity, which was maximal at a dose of 1 microgram/kg per min; arterial levels fell more steeply than venous ones. Angiotensin II disappeared in parallel with the drop in converting enzyme. Renal blood flow, on the other hand, began to increase only when 3 micrograms/kg per min was given, and no further changes occurred with the highest dose. Intra-arterial blood pressure fell only when the highest dose was given. Renin secretion tended to increase, but changes were not statistically significant. It is concluded that systemic suppression of converting enzyme is needed for renal vasodilatation to occur. However, the renal vascular response comes well before blood pressure falls.