Fatty Acid Composition of Plasma Lipids

H YPERLIPEMIA develops in cholesterol-fed rabbits accompanied after several weeks by lipid infiltration of the intima of the aorta.’ In contrast, the even higher plasma lipid levels obtained by repeated injections of the nonionic surfactant Triton WR-1339 are not associated with similar vascular lesions.’ This finding has aroused much interest, and several authors have studied the kinetic aspects and mechanism of this type of hyperlipemia. After injection with Triton, plasma tnglycenides immediately begin to rise, and an increase of phospholipids and both free and ester cholesterol follows with a delay of several hours.3 In the course of sustained treatment, triglycerides amount to over half of the total plasma lipids, while phospholipid values are higher than those of cholesterol ; the relative amount of free cholesterol is also unusually high.4 This lipid pattern is entirely different from that in the lipemia induced by cholesterol feeding, in which half of the lipid material is present as esterified cholesterol, and the phospholipid : cholesterol ratio is reversed. This reversed ratio has been suggested to be a major cause of the atherogenic effect of cholesterol feeding.’ Both types of lipemia are also different as