The effects of ethanol concentration on glycero-3-phosphate accumulation in the perfused rat liver. A reassessment of ethanol-induced inhibition of glycolysis using 31P-NMR spectroscopy and HPLC.
The dose-dependent effect of ethanol on the hepatic metabolism of the perfused rat liver has been investigated by (a) 31P-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 mumol 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 31P 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.
Masson
S
S
Centre de Résonance Magnétique Biologique et Médicale (URA CNRS 1186), Faculté de Médecine de la Timone, Marseille, France.
Desmoulin
F
F
Sciaky
M
M
Cozzone
P J
PJ
D000085:Acetates / Q000378:metabolism; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000378:metabolism / Q000494:pharmacology*; D005994:Glycerophosphates / Q000378:metabolism*; D006019:Glycolysis / Q000187:drug effects*; D007773:Lactates / Q000378:metabolism; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009243:NAD / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D010477:Perfusion; D010759:Phosphorus Isotopes; D011773:Pyruvates / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D000085:Acetates; D005994:Glycerophosphates; D007773:Lactates; D010759:Phosphorus Isotopes; D011773:Pyruvates; D009243:NAD; D000431:Ethanol; D010100:Oxygen