LIPID HYDROPEROXIDE-INDUCED MITOCHONDRIAL DYSFUNCTION FOLLOWING ACUTEETHANOL INTOXICATION IN RATS - THE CRITICAL ROLE FOR MITOCHONDRIAL REDUCED GLUTATHIONE

It has been found that acute ethanol (EtOH) intoxication of rats cause d depletion of mitochondrial reduced glutathione (GSH) of approximatel y 40%. A GSH reduction of similar extent was also observed after the a dministration to rats of buthionine sulphoximine (BSO), a specific inh ibitor of GSH synthesis. Combined treatment with BSO plus EtOH further decreased mitochondrial GSH up to 70% in comparison to control. Norma l functional efficiency was encountered in BSO-treated mitochondria, a s evaluated by membrane potential measurements during a complete cycle of phosphorylation. In contrast a partial loss of coupled functions o ccurred in mitochondria from EtOH- and BSO plus EtOH-treated rats. The presence in the incubation system of either GSH methyl monoester (GSH -EE), which normalizes GSH levels, or of EGTA, which chelates the avai lable Ca2+ partially restores the mitochondrial phosphorylative effici ency. Following EtOH and BSO plus EtOH intoxication, the presence of f atty-acid-conjugated diene hydroperoxides, such as octadecadienoic aci d hydroperoxide (HPODE), was detected in the mitochondrial membrane. E xogenous HPODE, when added to BSO-treated mitochondria, induced, in a concentration-dependent system, membrane potential derangement. The pr esence of either GSH-EE or EGTA fully prevented a drop in membrane pot ential. The results obtained suggest that fatty acid hydroperoxides, e ndogenously formed during EtOH metabolism, brought about non-specific permeability changes in the mitochondrial inner membrane whose extent was strictly dependent on the level of mitochondrial GSH.