Mechanisms of renal vasodilation after protein feeding: role of the renin-angiotensin system.
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.
Woods
L L
LL
Division of Nephrology and Hypertension, Oregon Health Sciences University, Portland 97201-3098.
D000804:Angiotensin II / Q000097:blood; D000818:Animals; D001783:Blood Flow Velocity; D002216:Captopril / Q000494:pharmacology; D004044:Dietary Proteins / Q000008:administration & dosage*; D004231:Diuresis; D004285:Dogs; D005260:Female; D005919:Glomerular Filtration Rate; D007668:Kidney / Q000098:blood supply*; D008460:Meat; D009318:Natriuresis; D012083:Renin / Q000097:blood; D012084:Renin-Angiotensin System / Q000502:physiology*; D014664:Vasodilation / Q000502:physiology*
D004044:Dietary Proteins; D000804:Angiotensin II; D002216:Captopril; D012083:Renin