THE EFFECTS OF ETHANOL CONCENTRATION ON GLYCERO-3-PHOSPHATE ACCUMULATION IN THE PERFUSED-RAT-LIVER - A REASSESSMENT OF ETHANOL-INDUCED INHIBITION OF GLYCOLYSIS USING P-31-NMR SPECTROSCOPY AND HPLC

The dose-dependent effect of ethanol on the hepatic metabolism of the perfused rat liver has been investigated by (a) P-31-NMR spectroscopy for the follow-up of intracellular phosphorylated metabolites and (b) HPLC for compounds released in the effluents. Perfusion of livers from fed rats with ethanol induced an increase in the level of sn-glycerol 3-phosphate and net accumulations of 3.30 +/- 0.33 and 0.69 +/- 0.15-mu-mol x g-1 wet liver were reached after 20 min, for 70 mM and 0.5 mM ethanol, respectively. sn-Glycerol-3-phosphate accumulation was fully detected by P-31 NMR as indicated by comparing quantitations based on NMR and biochemical assays. Ethanol administration up to a concentration of 10 mM induced a dose-dependent decrease in the release of lactate + pyruvate by the liver. Lactate release decreased from 1129 +/- 39 to 674 +/- 84 nmol x min-1 x g-1, while pyruvate decreased from 230 +/- 9 to 6.2 +/- 0.4 nmol x min-1 x g-1, after 20 min of perfusion with 10 mM ethanol. Nevertheless, the flux through 6-phosphofructo-1-kinase, as measured by both the accumulation of sn-glycerol 3-phosphate and release of lactate + pyruvate, was not affected in the early phase of ethanol oxidation. Finally, data obtained from oxygen consumption, the release of acetate and the accumulation of sn-glycerol 3-phosphate do not support the involvement of the microsomal ethanol-oxidizing system in the catalysis of ethanol oxidation, even at high doses of alcohol.