Pathogenesis of Ethanol-induced Fatty Liver. 3. in Vivo and Vitro Effects of Ethanol on Hepatic Fatty Acid Metabolism in Rats.

Addition of ethanol to rat liver slices enhanced triglyceride, phospholipid, and fatty acid synthesis from acetate-l-C1' and pyr~vate-2-C~~ by liver slices. The type of fatty acid synthesized (i.e., primarily saturated) was not altered by the presence of ethanol. These effects of ethanol on liver slices are probably not germane to the induction of fatty liver, since they were not observed after ethanol administration to the intact animal. The fatty acids accumulating in the liver after oral administration of ethanol consisted primarily of unsaturated fatty acids similar to those found in adipose tissue; the incorporation of circulating free fatty acids into hepatic triglycerides was increased. Also, the amount and rate of triglyceride formation from saturated and unsaturated fatty acids were significantly increased in liver homogenates and microsomes after ethanol administration but not upon in vitro addition of ethanol to liver slices. In view of the differences between the in vitro and in vivo effects of ethanol, experiments based solely on the action of ethanol in vitro must be interpreted with caution in elucidating the pathogenesis of the ethanol-induced fatty liver.