Evaluation of the metabolizing capacity of S9 liver preparations from rats and mice using a test with Salmonella typhimurium TA100.

The S9 phenobarbital-induced preparations from Albino rats and 6 strains of inbred and outbred Pzh: SFISS mice were tested by an Ames test for their ability to metabolize the two promutagens 2-aminofluorene (2AF) and cyclophosphamide (CP), and to influence the mutagenic activity of the two directly acting mutagens methyl methanesulphonate (MMS) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). 2AF showed a mutagenic activity after incubation with all kinds of microsomal preparations. S9 from B10. mice (Ah+Ah+) was twice as active as that from D2.BN mice (Ah- Ah-). CP was mutagenic exclusively in the presence of S9 from Pzh: SFISS or B10. mice and from rats. Neither fraction deactivated significantly the mutagenicity of MMS. Microsomal preparations from Albino rats and outbred mice were most active in deactivating the mutagenicity of MNNG.