Conversion of procarcinogens to mutagens by the S-9 fraction from the liver of rainbow trout (Salmo gairdneri): inducibility with PCB, 3-methylcholanthrene and phenobarbital and inhibition by metyrapone and alpha-naphthoflavone.

S-9 fractions from the liver of rainbow trout were found to convert 2-aminoanthracene and 2-acetylaminofluorene to mutagenic intermediates in the Salmonella/microsome test. The S-9 fractions from the liver of rainbow trout treated with either PCB or 3-methylcholanthrene enhanced the mutagenicity of 2-aminoanthracene and 2-acetylaminofluorene, and converted benzo(a)pyrene to mutagenic intermediates. Treatment of rainbow trout with phenobarbital failed to enhance the mutagenicity of these carcinogens. alpha-Naphthoflavone strongly inhibited the mutagenicity of procarcinogens with the S-9 fractions from the liver of untreated or treated rainbow trout with PCB, 3-methylcholanthrene or phenobarbital, however metyrapone had little effect in vitro. These results demonstrate that rainbow trout have the capacity to convert procarcinogens to mutagenic intermediates and that the major part of this capacity is derived from a cytochrome P-450 system resembling the mammalian cytochrome P-448 system.