Early effects of 2-acetylaminofluorene and N-hydroxy-2-acetylaminofluorene on mitochondrial outer membrane enzyme activities of rat liver.

During the early stages of the carcinogen 2-acetylaminofluorene (2-AAF) feeding, there were marked decreases of hepatic mitochondrial type B monoamine oxidase (MAO) and kynurenine 3-hydroxylase activities in male rats, but not in female rats. The administration of N-hydroxy-2-AAF (N-OH-2-AAF), a proximate carcinogenic metabolite of 2-AAF, to male rats also resulted in the decrease of both enzyme activities. The findings indicate that type B MAO and kynurenine 3-hydroxylase which reside in the outer mitochondrial membranes are susceptible to 2-AAF during the early stages of its hepatocarcinogenesis.