[Comparative study on the mutagenic activity of rat liver and bladder S9 by fluctuation test]

Mutagenicity of seven aromatic amines, two heterocyclic amines, two azo compounds and one polycyclic aromatic hydrocarbon was examined with a fluctuation test modified by Gatehouse. The test was performed by using Salmonella typhimurium TA98 in the presence of liver and bladder S9 from PCB pretreated rats. Seven out of 12 compounds showed mutagenic activities with liver S9 and seven with bladder S9. Benzidine, 3-methylcholanthrene and 2-acetylaminofluorene showed a negative response with bladder S9 but a positive response with liver S9. The mutagenicity of the seven compounds observed with bladder S9 had a lower sensitivity than with liver S9. 3-Amino-1,4-dimethyl-5H-pyrido[4,3-b]indole and 3-amino-1-methyl-5H-pyrido[4,3-b]indole showed mutagenic activity at lower concentrations than the other compounds which showed mutagenic activity either with bladder S9 or liver S9. Mutagenicity of 3-methylcholanthrene was observed at high concentration only in the presence of liver S9. The findings from the present study suggested that aromatic amines, heterocyclic amines and polycyclic aromatic hydrocarbons were more likely to be activated to strong mutagens with liver S9 than with bladder S9.