Cholesterol feeding does not alter renal hemodynamic response to
acetylcholine and angiotensin ii in rabbits.
Carroll, Joan F., H. Leland Mizelle, Kathy Cockrell, Jane F.
Reckelhoff, Ben R. Clower, and Joey P. Granger.
Department of Physiology and Biophysics, University of Mississippi
Medical Center, 2500 North State Street, Jackson, Mississippi 39216
-4505
APStracts 3:0372R, 1996.
Aortic ring studies have demonstrated a decrease in endothelium
-dependent relaxation or an enhanced response to vasoconstrictors in
rabbits fed a high cholesterol diet. Whether such abnormalities exist
in the renal circulation is unclear. The purpose of this study was to
determine functional renal responses to acetylcholine (ACh) or
angiotensin II (AngII) infusion in anesthetized rabbits after 8-10
weeks of either a control diet (n=6 ACh; n=6 AngII) or a 1%
cholesterol diet (n=7 ACh; n=7 AngII). Mean arterial pressure (MAP),
renal blood flow (RBF), and glomerular filtration rate (GFR) were
measured. Renal vascular resistance (RVR) was calculated as MAP/RBF.
For AngII experiments, captopril (15[mu]g/kg/min) was infused to
suppress endogenous AngII production. After two control clearance
periods, either ACh (1[mu]g/kg/min) or AngII (0.5 ng/kg/min) was
infused into the renal artery; RBF was allowed to stabilize prior to
experimental clearances. RBF increased with ACh (control: 25+/-2 to
39+/-2; cholesterol: 26+/-2 to 40+/-3 ml/min) and decreased with
AngII infusions (control: 40+/-4 to 25+/-3; cholesterol: 36+/-3 to
24+/-2 ml/min). Nitrate/nitrite excretion also increased with ACh
infusion (control: 2.3+/-1.0 to 5.2+/-1.8; cholesterol: 2.3+/-0.3 to
6.0+/-1.3 nmol/kg/min). However, there were no significant
differences between control and cholesterol groups in either
response. GFR was unaltered during ACh and AngII infusions. MAP, RVR,
and urinary sodium and potassium excretion did not differ between
groups in response to either drug. These results suggest that despite
significant hypercholesterolemia and large vessel atherosclerosis,
both nitric oxide-induced vasodilation and endothelial-dependent
modulation of AngII vasoconstriction in the renal circulation are
unaffected by cholesterol feeding.
Received 24 March 1996; accepted in final form 8 October 1996.
APS Manuscript Number R177-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996