diethyl-maleate and 6-hydroxy-2-5-7-8-tetramethylchroman-2-carboxylic-acid

To characterize the role of oxidative stress in cultured rat sinusoidal endothelial cells, we studied the production of superoxide after reoxygenation, the relationship of reduced glutathione (GSH) levels to cell injury, and the protective efficacy of antioxidants. Hypoxia (pO(2) 1-2 mm Hg) was achieved by culturing cells under 95% N(2)5% CO(2) for 4 hours. Reoxygenation was then reestablished, and viability was determined at 24 hours by trypan blue exclusion; putative protective agents were added at the time of reoxygenation (4 hours). As previously reported, reoxygenation after 4 hours hypoxia accentuated sinusoidal cell death fourfold compared with hypoxic or normoxic controls (P <.0001). Superoxide was not produced on reoxygenation, and superoxide dismutase provided no protection against reoxygenation injury. Cellular levels of GSH fell to 37 +/- 4% of normoxic controls (P <.0001) following reoxygenation. These changes were essentially abrogated by Trolox (Aldrich Chemical Co., Milwaukee, WI) and dimethyl sulfoxide, both of which also completely protected against reoxygenation injury. When cellular GSH levels were lowered by addition of diethylmaleate (which conjugates GSH), this reduced the viability of endothelial cells cultured under normoxic conditions and greatly augmented reoxygenation injury. Conversely, addition of exogenous GSH partially protected endothelial cells against hypoxia-reoxygenation injury. Desferrioxamine also protected against reoxygenation injury, but catalase was only partly protective. It is concluded that sinusoidal endothelial cells undergo significant intracellular oxidative stress following reoxygenation, and their viability is critically dependent on GSH levels. Reactive oxygen species are likely mediators of oxidative stress in hepatic sinusoidal endothelial cells.

Topics: Animals; Antioxidants; Cell Death; Cell Hypoxia; Cells, Cultured; Chromans; Dimethyl Sulfoxide; Endothelium, Vascular; Free Radical Scavengers; Glutathione; Liver; Male; Maleates; Oxidative Stress; Oxygen; Rats; Rats, Wistar; Superoxide Dismutase; Superoxides

The mechanisms of bromobenzene and iodobenzene hepatotoxicity in vivo were studied in mice. Both the intoxications caused a progressive decrease in hepatic glutathione content. In both instances liver necrosis was evident only when the hepatic glutathione depletion reached a threshold value (3.5-2.5 nmol/mg protein). The same threshold value was evident for the occurrence of lipid peroxidation. Similar results were obtained in a group of mice sacrificed 15-20 hours after the administration of diethylmaleate, a drug which is mainly conjugated with hepatic glutathione without previous metabolism. The correlation between lipid peroxidation and liver necrosis was much more significant than that between covalent binding and liver necrosis. This fact supports the view that lipid peroxidation is the major candidate for the liver cell death produced by bromobenzene intoxication. Moreover, a dissociation of liver necrosis from covalent binding was observed in experiments in which Trolox C (a lower homolog of vitamin E) was administered after bromobenzene poisoning. The treatment with Trolox C, in fact, almost completely prevented both liver necrosis and lipid peroxidation, while not changing at all the extent of the covalent binding of bromobenzene metabolites to liver protein.

Topics: Alanine Transaminase; Animals; Aspartate Aminotransferases; Bromobenzenes; Chemical and Drug Induced Liver Injury; Chromans; Glutathione; Iodobenzenes; Lipid Peroxides; Liver; Liver Diseases; Male; Maleates; Mice; Necrosis; Proteins; Rats; Rats, Inbred Strains