Glucocorticoid-induced alterations in phosphatidylcholine metabolism in mouse lymphoma cells, L5178Y, in vitro.

the absence of the steroid. In both, controls as well as hormone-treated cultures, Chromatographie separation of the acid-soluble fraction revealed that 95 to 98% of the radioactivity was associated with phosphorylcholine and that only a small amount was present as either cytidine diphosphate choline or choline. The labeled material in the lipid fraction consisted mainly of phosphatidylcholine (96 to 97%) with the remaining radioactivity as either lysophosphatidylcholine or sphingomyelin. Under such conditions the inhibi tion of choline incorporation was detected as early as 10 min after steroid addition to the labeling medium. The inhibition of choline-methyl-14C incorporation was