AJP - Heart and Circulatory Physiology, Vol 243, Issue 1 61-H67, Copyright © 1982 by American Physiological Society
Enhanced renal vasoconstriction in rats fed essential fatty acid-deficient diet
H. M. Sakr and E. W. Dunham
The effects of angiotensin II (ANG II) and norepinephrine (NE) on total
renal blood flow (RBF) were studied in rats fed an essential fatty acid
(EFA)-deficient diet. EFA deficiency was employed, as an alternative to the
use of cyclooxygenase inhibitors, to investigate the influence of
arachidonic acid metabolites on rat RBF. Intrarenal arterial (ira) bolus
doses of ANG II (2-16 ng) and NE (25-100 ng) elicited significantly greater
decrements in RBF and increments in renal vascular resistance in
anesthetized Sprague-Dawley rats fed EFA-deficient diets than in control
rats, which were fed EFA-adequate diets. Indomethacin (5 mg/kg iv) enhanced
the vasoconstrictor responses to ANG II and NE in rats fed the EFA-adequate
diet but not in rats fed the EFA-deficient diet. In rats fed regular
laboratory chow the renal vasoconstrictor response to ANG II was
potentiated after the administration of either indomethacin or naproxen (5
mg/kg iv). Methacholine and prostaglandins E2 and I2 caused dose-related
renal vasodilatation when injected (ira) over the dose range of 10-40 ng in
rats fed either the EFA-deficient or -adequate diets. The increased
responsiveness of the renal vascular bed to ANG II and NE in rats fed
EFA-deficient diets was not attributable to reduced vasodilator efficacy.
Collectively, these results suggest that the net effect of endoperoxide
products of arachidonic acid metabolism attenuates the vasoconstrictor
influences of exogenous ANG II and NE in the intact rat kidney.
