LOSS OF VIABILITY AFTER DISULFIRAM TREATMENT WITHOUT PRECEDING DEPLETION OF INTRACELLULAR GSH

Effects of disulfiram (DSF) on freshly isolated hepatocytes were examined. Its effects on the cellular reduced form of glutathione (GSH) were triphasic ; GSH decreased instantly after the addition of DSF, teturned to subnormal levels within 30 min, and then declined gradually. The initial decrease in GSH after DSF treatment and the subsequent recovery of GSH were accompanied by an increase and decrease in the oxidized form of gluiathione (GSSG), respectively. Decreases in cell viability brought about by 0.4 mM of DSF were correlated with the later gradual decrease in GSH. The loss of viability by DSF treatment seemed to appear when the intial GSH levels became lower than approximately 5 nmole/106 cells. Hepatocyte toxicity of DSF was potentiated by diethylmaleate (GSH depletor) and inhibited by N-acetylcysteine (GSH biosynthesis precursor). 1, 3-bis(2-chloroethyl)-1-nitrosourea (BCNU), an inhibitor of GSH reductase, inhibited the GSH recovery and potentiated the toxicity. Respiration of hebatocytes was also inhibited by DSF. Free sulfhydryl groups other than GSH showed similar changes to those of GSH. From these results, it seemed that DSF reacted with cellular GSH and other free sulfhydryl groups to form diethyldithiocarbamate and GSSG, GSSG was feduced back to GSH by glutathione reductase, and the detrease in the viability was dependent on the initial loss of GSH.