Effect of liver S9 from 3,4,5,3',4'-pentachlorobiphenyl-pretreated rats on the mutagenic activity of the various carcinogens toward Salmonella typhimurium TA 98.

Effects of liver 9000 X g supernatant fraction from 3,4,5,3',4'-pentachlorobiphenyl- and 2,4,5,2',4',5'-hexachlorobiphenyl-pretreated rats (PenCB-S9 and HexCB-S9, respectively) on the mutagenic activities of well-known carcinogens, benzo-[a]pyrene (BP), Glu-P-1 (2-amino-6-methyldipyrido [1,2-a:3',2'-d]imidazole), Trp-P-1 (3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole), and aflatoxin B1 (AFB), toward Salmonella typhimurium TA 98 have been described. Although the mutagenic activities of all of these carcinogens were enhanced by these S9, PenCB-S9 especially highly activated BP, Glu-P-1, and Trp-P-1. The ability of PenCB-S9 to activate the carcinogens was much higher than that of liver 9000 X g supernatant fraction from 3-methylcholanthrene-pretreated rats (MC-S9). PenCB-S9 enhanced the mutagenic activity of BP 8 times higher than MC-S9, while Glu-P-1 and Trp-P-1 were activated by PenCB-S9 twice as much as by MC-S9. Effect of HexCB-S9 on the mutagenic activities of the above-mentioned three carcinogens was much less than those of PenCB- and MC-S9 and a little higher than that of 9000 X g supernatant fraction from rats pretreated with phenobarbital. As for AFB, phenobarbital was the most potent inducer, and HexCB and PenCB were next to this. Data suggest that PenCB is a strong inducer of P-448 species which activate environmental toxicants.