Oxidation of mitochondrial DNA might be responsible for the persistence of structural and functional abnormalities of mitochondria in alcoholics after cessation of ethanol intake. Ethanol (4g/kg) was administered to mice, and DNA was isolated 3 h later from liver homogenates and mitochondria. Ethanol resulted in a 25% decrease of GSH in liver homogenates without increase in GSSG, oxidized proteins and 8-OHdG, respectively. In contrast, the content of carbonyls (23 +/- 1 vs 9 +/- 1 nmol/mg protein) and the extent of oxidation of DNA (49 +/- 8 vs 17 +/- 3 8-OHdG/10(5) dG) were significantly increased in mitochondria. Depletion of GSH with diethyl maleate also resulted in a 2-3 fold increase in the oxidation of proteins and DNA in mitochondria exclusively. Oxidation of DNA and low GSH together with the lack of DNA repair enzymes may result in permanent damage to the mitochondria of alcoholic subjects.