Regulation of Phospholipid Metabolism in Differentiating Cells from Rat Brain Cerebral Hemispheres in Culture

Cultured dissociated cells from rat embryo cerebral hemisphere iqcorporate [gH]and [U-14C]ethanolamine into cellular lipids. Nearly all radioactivity in the lipid fractions is incorporated into 1,2diacylethanolamine phosphoglycerides and I-alkenyl,P-acylethanolamine phosphoglycerides (plasmalogen). Kinetic data suggest that the rate of labeling of both ethanolamine phospholipids from the phosphorylethanolamine is similar. A relative increase of the plasmalogen labeling is observed when free ethanolamine is continually present in the medium. The rate of incorporation of label from ethanolamine and phosphorylethanolamine into lipids was measured using a double label technique. Based upon these studies, an independent labeling pattern of the ethanolamine moiety of plasmalogens is suggested. A relative delay for the incorporation of label in plasmalogens could be explained by the presence of a variety of cell types which may differ in their capacity for phospholipid biosynthesis. The rate of incorporation of phosphorylethanolamine into the phosphatidylethanolamine was not affected by the presence of high concentrations of either choline or serine.