Rapid and specific efflux of glutathione before hepatocyte injury induced by hypoxia.

Hypoxia caused the efflux of glutathione (GSH) from hepatocytes before membrane lysis occurred. Dithiothreitol (DTT), a thiol reductant, greatly increased the hypoxia induced GSH efflux as well as the subsequent membrane lysis. The NADH generating nutrients sorbitol and beta-hydroxybutyrate as well as ethanol also enhanced hepatocyte GSH efflux and cell injury, whereas on the other hand NADH oxidising metabolic intermediates, e.g., acetoacetate or the artificial electron acceptor methylene blue, partly prevented GSH efflux and membrane lysis. Hypoxia induced GSH efflux and cytotoxicity were also prevented by oxypurinol, a xanthine oxidase inhibitor, as well as by the polyphenolic antioxidant quercetin, suggesting that reactive oxygen species contributed to the GSH efflux and cell lysis. The above results suggest that reductive stress caused by hypoxia activates the redox sensitive sinusoidal GSH transporter that is likely responsible for the GSH efflux before membrane lysis ensues.