linoleic-acid and Hypertension--Renovascular

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.

Topics: Animals; Blood Pressure; Hypertension; Hypertension, Renovascular; Infusions, Intravenous; Linoleic Acid; Linoleic Acids; Male; Oleic Acid; Oleic Acids; Rats; Rats, Inbred Strains; Reference Values

To study the influence of dietary modification of prostaglandin synthesis on blood pressure regulation, the effects of dietary enrichment with linoleic acid were compared with standard rat chow in three groups of 24 rats before and after renal artery constriction and contralateral nephrectomy. Dietary supplementation with 40 energy% sunflower seed oil or linseed oil respectively caused incorporation of linoleic or linolenic acids into tissue phospholipids. Relative to the sunflower seed oil, the linseed oil diet led to inhibition of prostanoid synthesis in kidney, serum or aorta in vitro and urine in vivo. Rats on both oil-rich diets had lower blood pressures than rats on a standard diet. Thus, partial suppression of prostaglandin synthesis did not accelerate one-kidney, one clip Goldblatt hypertension, nor did sunflower oil protect against hypertension in a way that could be specifically ascribed to changes in prostaglandin synthesis.

Topics: 6-Ketoprostaglandin F1 alpha; alpha-Linolenic Acid; Animals; Aorta; Blood Pressure; Body Weight; Dietary Fats; Fatty Acids; Hypertension, Renovascular; Kidney; Linoleic Acid; Linoleic Acids; Linolenic Acids; Male; Prostaglandins; Rats; Thromboxanes