Influence of Fats and Fatty Acids on the Capillaries

Abstract

The capillary resistance and capillary permeability of the immature albino rat were studied under various dietary conditions. When the animals were fed a synthetic diet practically devoid of fat and fatty acids, or a synthetic diet containing 5% methyl stearate, the capillary resistance began to decline about the 50th day of the experiment and dropped to pathologically low levels. The difference amounted to 35 to 65 cm Hg,, depending on the initial level (35 to > 70 cm). If the same basic diet contained 5% corn oil, the capillary resistance remained normal. This drop in capillary resistance occurred simultaneously with the flattening of the weight curve, but before the characteristic manifestations of fat deficiency had developed. Among the manifestations of fat deficiency no caudal necrosis was ever encountered. A comparison between the capillary permeability of the animals showing abnormally low capillary resistance and that of the animals with normal capillary resistance indicated that the decrease in the capillary resistance of rats fed a fat-deficient diet or a diet containing methyl stearate was associated with an increase in the capillary permeability. The low capillary resistance of fat-deficient rats was promptly restored by minute amounts of linseed oil or cottonseed oil or pure linoleic acid. In testing for capillary resistance in the human being, a new factor influencing this phenomenon must be taken into consideration. This new factor involves dietary fat.