Cardiac lipid changes in rats fed oils enriched in saturates and their apparent relationship to focal heart lesions.

Weanling male Sprague-Dawley rats were fed diets containing 20% by weight corn, soybean or low erucic acid rapeseed oils or mixtures of the latter two with cocoa butter or triolein for 1, 2, 3 or 4 weeks. These diets previously had been fed to the same strain of rats for 16 weeks, and a reduction in the incidence of focal heart lesions had been observed with the addition of cocoa butter, but not triolein. The cardiac lipid classes and the fatty acid and alkenyl ethers of the cardiac phospholipids were analyzed to determine if changes could be attributed to the observed cardiopathological response, and at what time. Cardiac lipid classes changed during post-weaning development, but only triacylglycerol was diet-related. A number of fatty acid changes were observed in the cardiac phospholipids which reflected the relative concentration of saturates, monounsaturates, linoleic acid and linolenic acid in the diet, but only the changes in saturates and the C22 polyunsaturated fatty acids from the linolenic acid family appeared to be related to the incidence of focal heart lesions. Arachidonic acid and the total C22 polyunsaturated fatty acids remained fairly constant throughout the feeding trial. Cardiac diphosphatidylglycerol was least affected by dietary manipulation, while nervonic acid increased in cardiac sphingomyelin when small amounts of erucic acid were present in the diet. Fatty acid changes were essentially completed after one week on the experimental diets, whereas changes in the alkenyl ethers took two to three weeks.