Intracellular inhibition of catalase by alpha-methyldopa

The effect of preincubation with alpha-methyldopa on catalase-dependent decomposition of H2O2 was studied in isolated rat hepatocytes. A direct assay of catalase function was obtained by measurement of O2 production under anaerobic conditions following additions of H2O2. Both the total O2 produced and the maximal O2 concentration attained were decreased by preincubation with alpha-methyldopa. The results demonstrate that alpha-methyldopa-induced formation of Compound II is associated with loss of intracellular catalase activity. These results indicate that the hepatotoxicity of alpha-methyldopa may be related to an increased sensitivity to oxidative injury due to inhibited catalase function.