Modification of the Fatty Acid Composition of Ehrlich Ascites Tumor Cell Plasma Membranes

The fatty acyl group composition of Ehrlich ascites tumor cell plasma membranes was modified by feeding the tumor-bearing mice diets rich in either coconut or sunflower oil. When coconut oil was fed, the oleate content of the membrane phospholipids was elevated and the linoleate content reduced. The opposite occurred when sunflower oil was fed. Qualitatively similar changes were observed in the plasma membrane phosphatidylethanolamine, phosphatidylcholine and mixed phosphatidylserine plus phosphatidylinositol fractions. These diets also produced differences in the sphingomyelin fraction, particularly in the palmitic and nervonic acid contents. Unexpectedly, the saturated fatty acid content of the plasma membrane phospholipids was somewhat greater when the highly polyunsaturated sunflower oil was fed. The small quantities of neutral lipids contained in the plasma membrane exhibited changes in acyl group composition similar to those observed in the phospholipids. These fatty acyl group changes were not accompanied by any alteration in the cholesterol or phospholipid contents of the plasma membranes. Therefore, the lipid alterations produced in this experimental model system are confined to the membrane acyl groups.