Effect of ACE inhibition on pressor, renal vascular, and adrenal responses to infusion of angiotensin I in normal subjects eating a low-salt diet.
To examine the influence of angiotensin-converting enzyme (ACE) on pressor, renal vascular, and adrenal responses during angiotensin I (Ang I) infusion, we studied 10 normotensive, healthy men. Each was in balance with a 10-mEq sodium, 100-mEq potassium intake and was studied before and during ACE inhibition with enalapril. Ang I (3, 10, and 30 ng/kg/min) was infused in each subject. Then ACE inhibition was instituted with enalapril for 3 days, which induced the anticipated fall in blood pressure, plasma Ang II, and aldosterone concentration, and rise in renal plasma flow. During ACE inhibition only the 30-ng/kg/min Ang I dose raised plasma Ang II levels. There was a spectrum, however, in the end-organ response to Ang I during ACE inhibition. Responses of plasma aldosterone concentration and blood pressure were in excellent accord with the reduction in Ang II formation. On the other hand, responses of the renal blood supply were substantially less inhibited than anticipated. Under the conditions of this study, ACE inhibition led to nonuniform changes in the response to exogenous Ang I, suggesting intrarenal conversion of Ang I to Ang II.
Hollenberg
N K
NK
Department of Medicine, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
Fisher
N D
ND
Price
D A
DA
Williams
G H
GH
D000293:Adolescent; D000311:Adrenal Glands / Q000187:drug effects / Q000502:physiology*; D000328:Adult; D000450:Aldosterone / Q000097:blood; D000803:Angiotensin I / Q000008:administration & dosage*; D000804:Angiotensin II / Q000097:blood; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects*; D004039:Diet, Sodium-Restricted; D004656:Enalapril / Q000494:pharmacology*; D006801:Humans; D007262:Infusions, Intravenous; D007668:Kidney / Q000098:blood supply / Q000187:drug effects / Q000502:physiology; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012077:Renal Artery / Q000187:drug effects / Q000502:physiology*; D017595:Renal Plasma Flow / Q000187:drug effects; D012082:Renal Veins / Q000187:drug effects / Q000502:physiology*; D014661:Vasoconstriction / Q000187:drug effects*
D000806:Angiotensin-Converting Enzyme Inhibitors; D000804:Angiotensin II; D000450:Aldosterone; D004656:Enalapril; D000803:Angiotensin I