Physiological effects of varying dietary linoleic acid in spontaneously hypertensive rats

The effect of dietary variations in linoleic acid (LA) on the development of hypertension was studied in young male spontaneously hypertensive rats (SHR). All groups developed elevated systolic blood pressures, but after 7 weeks on the experimental diets the blood pressures of the rats fed the diet with a low LA content (0.17% as supplied by 8% coconut oil) were significantly lower than the group fed a high level of LA (9.5% as supplied by 17% corn oil) in the diet. Rats fed the high LA diet had increased urine output and developed a mild but persistent polydipsia. After 4 months on the experimental diets, potassium excretion was decreased in proportion to the amount of LA in the diet but sodium excretion was not altered. Serum potassium was significantly elevated in the group fed high LA after 5 months. The effects of LA on hypertension of SHR appear to be opposite to those observed during salt-induced hypertension. Since LA is the dietary precursor of the prostaglandins, the effects observed may be due to the availability of precursor for renal prostaglandin synthesis which has been reported to be altered in SHR.