Ethanol potentiates hypoxic liver injury: role of hepatocyte Na(+) overload.
Centrilobular hypoxia has been suggested to contribute to hepatic damage caused by alcohol intoxication. However, the mechanisms involved are still poorly understood. We have investigated whether alterations of Na(+) homeostasis might account for ethanol-mediated increase in hepatocyte sensitivity to hypoxia. Addition of ethanol (100 mmol/l) to isolated rat hepatocytes incubated under nitrogen atmosphere greatly stimulated cell death. An increase in intracellular Na(+) levels preceded cell killing and Na(+) levels in hepatocytes exposed to the combination of ethanol and hypoxia were almost twice those in hypoxic cells without ethanol. Na(+) increase was also observed in hepatocytes incubated with ethanol in oxygenated buffer. Ethanol addition significantly lowered hepatocyte pH. Inhibiting ethanol and acetaldehyde oxidation with, respectively, 4-methylpyrazole and cyanamide prevented this effect. 4-methylpyrazole, cyanamide as well as hepatocyte incubation in a HCO(3)(-)-free buffer or in the presence of Na(+)/H(+) exchanger blocker 5-(N,N-dimethyl)-amiloride also reduced Na(+) influx in ethanol-treated hepatocytes. 4-methylpyrazole and cyanamide similarly prevented ethanol-stimulated Na(+) accumulation and hepatocyte killing during hypoxia. Moreover, ethanol-induced Na(+) influx caused cytotoxicity in hepatocytes pre-treated with Na(+), K(+)-ATPase inhibitor ouabain. Also in this condition 4-methylpyrazole and 5-(N,N-dimethyl)-amiloride decreased cell killing. These results indicate that ethanol can promotes cytotoxicity in hypoxic hepatocytes by enhancing Na(+) accumulation.
Carini
R
R
Department of Medical Science, University 'A. Avogadro' of East Piedmont, Via Solaroli 17, 27100, Novara, Italy.
De Cesaris
M G
MG
Spendore
R
R
Albano
E
E
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D015687:Cell Hypoxia; D002469:Cell Separation; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003484:Cyanamide / Q000494:pharmacology; D000431:Ethanol / Q000037:antagonists & inhibitors / Q000633:toxicity*; D000077604:Fomepizole; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007511:Ischemia / Q000378:metabolism* / Q000473:pathology; D008099:Liver / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008107:Liver Diseases / Q000378:metabolism* / Q000473:pathology; D008297:Male; D010477:Perfusion; D011720:Pyrazoles / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000032:analysis / Q000378:metabolism*
D011720:Pyrazoles; D000431:Ethanol; D003484:Cyanamide; D000077604:Fomepizole; D000255:Adenosine Triphosphate; D012964:Sodium