Response of docosapentaenoic acids of rat heart phospholipids to dietary fat

Groups of male Holtzman strain rats were fed from weanling one of the following diets: 20% hydrogenated soybean fat (20% HF), and 20% HF plus 2%, 3% and 4% corn oil, respectively, for 20 weeks. The animals were killed, and the heart phospholipid fractions isolated by chromatographic procedures. The levels and distribution of the docosapolyenoic acids, especially 22∶5ω3, were compared among the animals fed the corn oil supplemented and nonsupplemented diets. Although dietary linolenate (18∶3ω3) level was very low in the nonsupplemented diet, 22∶5ω3 accounted for 8.4% of the total fatty acids of heart total phospholipids when this diet was fed-half the level of total eicosatetraenoic acids. The amounts of 22∶5ω3 were decreased by corn oil supplementation of the diet and got down to the “normal” range of 2.0–2.5% at corn oil supplementation levels greater than 2%. The docosapolyenoic acids were confined largely to the phosphatidylcholine and phosphatidylethanolamine classes of phospholipids. These findings are discussed from the standpoint of the structural role of the phospholipids in the heart subcellular fractions.