AJP - Renal Physiology, Vol 245, Issue 3 408-F415, Copyright © 1983 by American Physiological Society
Intrarenal angiotensin I conversion at normal and reduced renal blood flow in the dog
L. Rosivall, D. F. Rinder, J. Champion, M. C. Khosla, L. G. Navar and S. Oparil
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.
