AJP - Heart and Circulatory Physiology, Vol 257, Issue 2 611-H617, Copyright © 1989 by American Physiological Society
Effect of linoleic acid infusion on blood pressure in normotensive and hypertensive rats
S. R. Reddy, R. Talwalkar, J. Downs and T. A. Kotchen
Department of Medicine, West Virginia University School of Medicine, Morgantown 26506.
High dietary intake of linoleic acid lowers arterial pressure, and, in
vitro, linoleic acid inhibits the enzymatic activity of renin. The purpose
of the present study was 1) to evaluate the effect of intravenous infusion
of linoleic acid on blood pressure in normotensive and hypertensive
Sprague-Dawley rats and 2) to determine whether the hypotensive response to
linoleic acid infusion is caused by inhibition of circulating renin. Blood
pressure was decreased (P less than 0.01) by linoleic acid infusion in
normotensive sodium chloride-deprived animals and in animals with
two-kidney, one-clip hypertension. In contrast, linoleic acid infusion did
not affect blood pressure in normotensive rats on a "normal" or high sodium
chloride intake, in rats with deoxycorticosterone acetate (DOCA)-salt
hypertension, and in anephric rats. In sodium chloride-deprived rats, the
reduction of blood pressure by linoleic acid infusion was associated with
increased plasma renin activity (P less than 0.05); serum
angiotensin-converting enzyme activity was unchanged. The in vitro
enzymatic activity of exogenous renin in plasma of anephric rats was not
affected by linoleic acid infusion. In two-kidney, one-clip hypertensive
animals, pretreatment with indomethacin did not alter the hypotensive
response to linoleic acid. Thus, although linoleic acid infusion lowered
blood pressure in high renin but not in low renin states, the reduction of
blood pressure was not related to inhibition of circulating renin or to
alterations of endogenous prostaglandin biosynthesis.
