Intrarenal angiotensin I conversion at normal and reduced renal blood flow in the dog.
Intrarenal conversion of angiotensin I (ANG I) to angiotensin II (ANG II) under conditions of normal and reduced renal blood flow (RBF) elicited by constriction of the renal artery was examined in pentobarbital-anesthetized dogs. In eight animals, tracer doses of 125I-ANG I (5-12 pmol) were injected into the renal artery and 125I-ANG I, 125I-ANG II, and 125I-labeled metabolites were measured in renal venous effluent by high-voltage paper electrophoresis. The mean conversion of ANG I to ANG II during a single passage through the kidney was 21.8 +/- 2.1% at control RBF. When RBF was decreased by 25 and 53%, percent ANG I conversion was not altered significantly. In six dogs percent conversion of 125I-[Sar1, Ile5]ANG I, an ANG I analogue refractory to hydrolysis by aminopeptidases, was 18.1 +/- 1.7% at control RBF and did not change significantly when the RBF was reduced by 55%. Although there were severalfold increases in renal renin secretion rate and net ANG I generation rate during reduced RBF, net renal ANG II formation rate did not change significantly. These data indicate that there is substantial conversion of ANG I in a single passage through the dog kidney and that intrarenal ANG I conversion is independent of RBF even under conditions in which renin secretion rate and ANG I generation rate are increased severalfold.
D000803:Angiotensin I / Q000378:metabolism* / Q000494:pharmacology; D000804:Angiotensin II / Q000378:metabolism; D000806:Angiotensin-Converting Enzyme Inhibitors; D000809:Angiotensins / Q000378:metabolism*; D000818:Animals; D001794:Blood Pressure; D004151:Dipeptides / Q000494:pharmacology; D004285:Dogs; D015773:Enalaprilat; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects; D007668:Kidney / Q000378:metabolism*; D008297:Male; D011863:Radioimmunoassay; D012077:Renal Artery / Q000502:physiology; D012079:Renal Circulation
D000806:Angiotensin-Converting Enzyme Inhibitors; D000809:Angiotensins; D004151:Dipeptides; D000804:Angiotensin II; D000803:Angiotensin I; D015773:Enalaprilat