| Summary: | In vivo incorporation of choline-methyl-14C into liver lecithin and its biosynthetic precursors was studied in CCl4-treated rats. Radioactivity in cytidine diphosphoryl (CDP-)choline and lecithin was reduced to one-third of control levels, whereas that of phosphorylcholine was increased to 4.7 times control levels. Incorporation of phosphorylcholine-32P into lecithin by homogenates prepared from livers of CCl4-treated animals was reduced, but conversion of CDP-choline-32P to lecithin by the isolated microsomal fraction did not show any significant depression. A block in the synthesis of CDP-choline is indicated. The in vivo utilization of methionine for lecithin synthesis was not affected.After intravenous injection of palmitic acid-1-14C, radioactivity of triglycerides from microsomal and mitochondrial fractions was markedly lower than the controls, whereas radioactivity of triglycerides in the soluble fraction was greatly increased. Radioactivity of diglycerides changed from 0.5% of total lipids in the control to 10% of total lipids in CCl4-treated animals. Incorporation of palmitic acid into phospholipids was also suppressed.The results demonstrate that synthesis of both phospholipids and triglycerides is inhibited in rats 4-5 hr after CCl4 administration.
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