Induction of cytochromes P450 and mixed-function oxidase activity by polychlorinated biphenyls and β-naphthoflavone in carp ( Cyprinus carpio)

Abstract

1. 1. Hepatic microsomal ethoxyresorufin- O-deethylase and benzo(a)pyrene hydroxylase activities consistently were increased and cytochrome P450 content and ethoxycoumarin- O-deethykase activity sometimes were increased in carp injected with Aroclor 1254 or β-naphthoflavone as compared to corn oil vehicle alone. 2. 2. Hepatic microsomal deethylase activities and cytochrome P450 content were not significantly elevated by injection with 2,4,2',4'-tetrachlorobiphenyl as compared to corn oil above. 3. 3. Kidney microsomal deethylase activities as compared to corn oil injected were unaffected by these ag agents except that Aroclor 1254 significantly elevated ethoxyresorufin- O-deethylase activity. 4. 4. Control and induced hepatic microsomal benzo(a)pyrene hydroxylase activities were unaffected by metyrapone but were significantly inhibited by α-naphthoflavone added in vitro. 5. 5. Patterns of carp hepatic microsomal enzyme activities and responses to inhibitors resemble those seen in hepatic microsomes from 3-methylcholanthrene induced mammalian species, i.e. are cytochrome P448-like.