AJP - Regulatory, Integrative and Comparative Physiology, Vol 264, Issue 3 601-R609, Copyright © 1993 by American Physiological Society
Mechanisms of renal vasodilation after protein feeding: role of the renin-angiotensin system
L. L. Woods
Division of Nephrology and Hypertension, Oregon Health Sciences University, Portland 97201-3098.
These studies were designed to determine the importance of the
renin-angiotensin system (RAS) in the renal hemodynamic response to acute
protein feeding. In chronically instrumented conscious dogs on a normal (80
meq/day) sodium intake, a 10 g/kg meal of raw beef caused glomerular
filtration rate (GFR) to increase from 68 +/- 6 to 86 +/- 6 ml/min and
effective renal plasma flow (ERPF) to increase from 211 +/- 14 to 263 +/-
15 ml/min. Plasma renin activity (PRA) was 0.44 +/- 0.14 ng ANG I.ml-1 x
h-1 and did not change significantly. When the protocol was repeated during
infusion of captopril, GFR increased from 67 +/- 11 to 97 +/- 10 ml/min,
and ERPF rose from 264 +/- 74 to 392 +/- 82 ml/min after the meat meal. The
dogs were then placed on a low-salt diet (approximately 7 meq/day) to
physiologically activate the RAS. In sodium-restricted dogs, GFR increased
from 71 +/- 7 to 104 +/- 10 ml/min and ERPF increased from 226 +/- 15 to
299 +/- 21 ml/min after the meat meal. PRA was 3.1 +/- 1.0 ng ANG I.ml-1 x
h-1 and did not change. Thus neither blockade of the RAS with captopril nor
activation of the RAS by salt restriction reduced the renal hemodynamic
response to a meat meal. These data indicate that the RAS is relatively
unimportant in the renal hemodynamic response to acute protein feeding.
