Damage to protein synthesis concurrent with lipid peroxidation in rat liver slices: Effect of halogenated compounds, peroxides, and vitamin E

Abstract

Protein synthesis and lipid peroxidation were evaluated in rat liver slices incubated in the presence of oxidants and protein synthesis inhibitors. Protein synthesis by rat liver slices was evaluated by [ 3H]leucine incorporation into the trichloroacetic acid (TCA)-insoluble material, and lipid peroxidation was evaluated by thiobarbituric acid-reactive substances (TBARS) released into the incubation medium. Protein synthesis inhibition by bromotrichloromethane (BrCCl 3) or t-butyl hydroperoxide ( t-BOOH) depended on the incubation time and oxidant concentration. [ 3H]Leucine incorporation was decreased to 20 and 47% of control values and TBARS were enhanced from the control value of 16.9 to 45.3 and 62.5 nmol/g of liver by incubation for 1 h with 1 m m BrCCl 3 and t-BOOH, respectively. Following incubation, both protein synthesis damage and lipid peroxidation were decreased in control and oxidant-treated slices prepared from rats injected with 200 mg of dl-α-tocopherol/kg of body wt. Release of lactate dehydrogenase was not enhanced by oxidant treatment. Protein synthesis inhibitors reversibly decreased [ 3H]leucine incorporation, but the effect of oxidants on protein synthesis was irreversible. Cumene hydroperoxide and methyl ethyl ketone peroxide, but not hydrogen peroxide, damaged protein synthesis and induced lipid peroxidation. The ability of carbon tetrabromide, benzyl chloride, bromoform, bromobenzene, carbon tetrachloride, chloroform, dichloromethane, and bromochloromethane to inhibit protein synthesis was correlated with their ability to induce lipid peroxidation, and with their LD 50. The results suggest that oxidant-induced lipid peroxidation and protein synthesis damage occurred concurrently, and that protein synthesis inhibition may be involved in cell injury or death mediated by free radicals.