Influence of catalase on the radiation sensitizing effect of misonidazole

The radiation modifying action of misonidazole and catalase was investigated in Bacillus megaterium spores at various oxygen concentrations. Catalase (120 micrograms/ml) decreased the radiation sensitizing action of misonidazole. Misonidazole as an electron affinic radiation sensitizer enhanced the build up of H2O2, thus promoting the reaction with catalase. Protection by catalase was not enough to eliminate the total radiation sensitizing effect of misonidazole.