Augmented acute hypotensive effect of dihydralazine and clonidine after linoleic acid rich diet in normotensive conscious rats.

The influence of dietary linoleic acid (LA) content on the cardiovascular effects of dihydralazine and clonidine was investigated in conscious rats. Male normotensive rats were fed either a diet rich in linoleic acid (LA) (13.3 cal-% LA) or a diet deficient in LA (0.5 cal-% LA) for a period of 5 months beginning in the pregnant mothers. Dihydralazine (1 mg/kg iv) or clonidine (10 micrograms/kg iv) were injected into conscious rats and blood pressure and heart rate were studied during a 20 min investigation period. The blood pressure lowering effects were higher in the rats fed the LA rich diet than in those fed the LA deficient diet 2, 5, 10 and 20 min after dihydralazine and 5 min after clonidine injection. The increase in heart rate per 10 mmHg blood pressure reduction after dihydralazine injection was lower in the rats fed on the diet rich in LA. We assume that the change in the cardiovascular effects of dihydralazine and clonidine by dietary LA may be caused by alterations of endogenous prostaglandin biosynthesis and sympathetic activity.