[Dietary alpha-linolenic acid and arterial pressure in the rat]

The effect of dietary alpha-linolenic acid (18: 3 n-3) upon the arterial pressure of rats has been studied. Three experiments were carried out on rats of different ages that were fed a diet containing alpoha-linolenic acid in the form of Primor oil (rapeseed oil low in erucic acid). Control animals were fed a peanut oil diet and a third group of rats was fed a low-lipid, commercial diet. The arterial pressure of the rats was periodically measured. After a two- or three-month period (depending on the experiment), the rats were killed. Some of the livers were taken out and their fatty acids analysed. Comparing the results obtained in the rats fed on the alpha-linolenic acid diet with those of the control rats, we found that: (1) Dietary alpha-linolenic acid brought about no noticeable effect upon arterial pressure. (2) The arachidonic: linoleic (w/w) ratio in the liver lipids was lowered in the animals that had received alpha-linolenic acid, indicating a partial inhibition of the biosynthesis of arachidonic acid in these rats. Two hypotheses have been tentatively proposed to explain the absence of hypertensive effect following the administration of alpha-linolenic acid, in spite of its inhibitory effect upon the conversion of linoleic acid into polyunsaturated fatty acids which are the precursors of prostaglandins in rats.