Tert-butyl hydroperoxide (BHP), hydrogen peroxide and diamide caused a rapid and simultaneous release of glutathione disulfide (GSSG) and K + in the isolated perfused rat liver. Both BHP-induced effluxes were suppressed by prior depletion of hepatic glutathione, but not by co-infusion of desferrioxamine which prevented lipid peroxidation and cell death. High K + media decreased the GSSG efflux even though hepatic GSSG levels remained high. The GSSG and K ÷ effluxes were repeatable if cellular K + recovered after a short BHP exposure. Ouabain inhibited the K ÷ re-uptake and decreased the response to repeated BHP challenge. Thus, sinusoidal efflux of GSSG under oxidative stress may be driven by a K + gradient.Glutathione disulfide efflux; K + efflux; Oxidative stress; Isolated perfused rat liver

ABSTRACT-The tert-butyl hydroperoxide (BHP)-induced release of oxidized glutathione (GSSG) and K+ was studied in relation to lipid peroxidation and cell death using isolated perfused rat livers. Infusion of BHP into the perfused liver resulted in an early and simultaneous release of GSSG and K+ and a sustained release of thiobarbituric-acid-reactive substances (TBARS) into the effluent perfusate, which was followed by further prenecrotic leakage of K+ followed by lactic dehydrogenase (LDH). These actions of BHP were not significantly affected by cutting or ligating the bile duct, and they were potentiated by omitting Ca" from the perfusion medium. Co-infusion of desferrioxamine, propyl gallate and diethyldithiocarbamate suppressed TBARS release as well as the later leakage of K+ and LDH. Desferrioxamine was also effective under Ca"-free conditions. N,N diphenyl p-phenylenediamine inhibited TBARS release, but it was not protective against cell death, although there was some delay. The action of dithiothreitol was only moderate. On the other hand, leakage of TBARS, K+ (prenecrotic) and LDH was enhanced by cysteamine and ~-mercaptoethanol and most markedly enhanced by ferrous iron. However, none of these agents markedly affected the early release of GSSG and K+. These observations, which support our previous findings, suggest that the early and coupled sinusoidal efflux of GSSG and K+ caused by BHP is independ ent of lipid peroxidation and cell death and that they represent a physiological mechanism of GSSG release. The results also suggest that lipid peroxidation is not the sole cause of BHP-induced cell death.

No abstract