Cytoprotective effect of reduced glutathione in hydrogen peroxide-induced endothelial cell injury

The kinetic effects of hydrogen peroxide (H₂O₂) on cultured endothelial cells isolated from bovine carotid artery were studied. The cytoprotective effects of glutathione (GSH) on H₂O₂-induced cell injury were also investigated. H₂O₂-induced a dose- and time-dependent cell injury in cultured endothelial cells. H₂O₂-induced cell injury was blocked by simultaneous treatment by catalase, but not by superoxide dismutase. H₂O₂ also induced endogenous PGI₂ biosynthesis, and the maximum PGI₂ production was reached after 1 h treatment. Stimulation of PGI₂ production was parallel with arachidonate release from H₂O₂-treated cells. However the prostaglandin biosynthesis enzyme activity in cells was inhibited by H₂O₂ treatment. When the cells were treated with GSH, the intracellular GSH reached a plateau after 3 h treatment. Both H₂O₂-induced cell injury and PGI₂ production were significantly inhibited by the 3 h pretreatment with GSH. The cytoprotective effect of GSH was completely inhibited by buthionine sulfoximine which is a specific inhibitor of γ-glutamylcysteine synthetase. The results indicate that the cytoprotective effect of GSH on H₂O₂-induced cell injury in cultured bovine carotid artery endothelial cells depends on the increase in intracellular GSH content.