METABOLISM OF PALMITATE IN PERFUSED RAT-LIVER - EFFECT OF LOW AND HIGH ETHANOL CONCENTRATIONS AT VARIOUS CONCENTRATIONS OF PALMITATE IN THE PERFUSION MEDIUM

The effect of ethanol on the metabolism of [1-14C]palmitate in rat liver was investigated in a single-pass perfusion system at concentrations of 10 mM- or 80 mM-ethanol and 0.2 mM- or 1 mM-palmitate. After the perfusion the hepatic lipid was isolated in subcellular fractions. The two major fractions contained triacylglycerol from cytoplasmic droplets and from endoplasmic reticulum plus Golgi apparatus respectively. In experiments with 0.2 mM-palmitate perfusion with 10 mM- or 80 mM-ethanol did not measureably increase the esterification, and the oxidation was markedly decreased and the fatty acid uptake was not affected. Perfusion with ethanol, at 1 mM-palmitate, increased the fatty acid uptake, increased esterification and decreased oxidation. The effects of 10 mM- and 80 mM-ethanol were similar. The incorporation of [1-14C]palmitate into triaglycerol in cytoplasmic lipid droplets was not affected statistically significantly by ethanol. Ethanol increased the incorporation of [1-14C]palmitate into di- and tri-acylglycerol in the membranous fraction. Estimated chemically, the contents of di- and tri-acylglycerol were only slightly affected by ethanol. These results suggests that the effect of ethanol was to increase the turnover of fatty acids in triacylglycerol than to increase its accumulation. The results indicate that an increased concentration of fatty acids is more important for the formation of acute fatty liver in fed rats than are the direct effects of ethanol on hepatic fatty acid metabolism.