1. 1. More unsaturated fatty acid was present in hepatic triglyceride, phosphatidylcholine and phosphatidylethanolamine in rats fed corn oil than in those fed coconut oil. 2. 2. In corn oil-fed rats, ethanol increased the relative amounts of unsaturated fatty acids in hepatic triglyceride and phosphatidylcholine without altering their proportion in phosphatidylethanolamine. 3. 3. In coconut oil-fed rats, ethanol increased the relative amount of saturated fatty acids in hepatic triglyceride, but failed to change the proportion of saturated fatty acids in phosphatidylcholine or phosphatidylethanolamine. 4. 4. Transferase activity in rat liver microsomes was assayed using CoA derivatives of palmitic, stearic, oleic, linoleic and arachidonic acids as fatty acyl donors and α- and β-lysophosphatidylcholine and α- and β-lysophosphatidylethanolamine as fatty acyl acceptors. Markedly increased rates of transfer of unsaturated fatty acids onto α-lysophosphatidylcholine and diminished rates of transfer of saturated fatty acids onto β-lysophosphatidylcholine were observed in ethanol-treated rats fed corn oil. Ethanol failed to produce similar changes in rats fed coconut oil, however, suggesting that the fatty acid composition of dietary triglyceride modified the response of these acyltransferases to ethanol. 5. 5. Ethanol increased slightly the rates of transfer of both saturated and unsaturated fatty acids onto α-lysophosphatidylethanolamine in rats fed corn oil, but had little effect on the transfer of fatty acids onto (3-lysophosphatidylethanolamine. 6. 6. These effects of ethanol on in vitro acyltransferase activities correlate with changes in the saturated and unsaturated fatty acid composition of phosphatidylcholine, as well as the lack of change of phosphatidylethanolamine, in ethanol-treated rats.
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