© 1982 Oxford University Press
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Reconstitution of Some Biochemical and Toxicological Effects of Commercial Mixtures of Polybrominated Biphenyls
Department of Biochemistry, Michigan State University East Lansing, MI 48824
Reconstitution of Some Biochemical and Toxicological Effects of Commercial Mixtures of Polybrominated Biphenyls. Dannan, G.A., Mileski, G.J. and Aust, S.D. (1982). Fundam. Appl. Toxicol. 2:322-326. Male rats were administered a single ip injection (90 mg/kg) of Firemaster FF-1, Firemas-ter BP-6, or a reconstituted mixture formulated to resemble Firemaster BP-6 to see if the pure congeners account for the toxicity of Firemaster. The reconstituted mixture was composed of nine purified congeners, totalling nearly 97% of either Firemaster mixture. The treatments were compared for their effects on hepatic microsomal drug metabolizing enzymes, body weight gain, and on the weights of selected organs one week after treatment. NADPH-cytochrome c reductase, aminopyrine-N-demethylase, and epoxide hydrase, typically induced by phenobarbital, were similarly induced by all mixtures. The content of cytochrome P-450 hemopro-teins was nearly quadrupled by all treatments; however, the absorption maxima of the difference spectra were shifted more by Firemaster BP-6 and the reconstituted mixture than by Firemaster FF-1. In agreement with this observation, Firemaster BP-6 and the reconstituted mixture also more significantly increased the cytochrome P450 ethyl isocyanide 455:430 nm difference spectral ratio, and the activities of benzo[a]pyrene hydroxylase, and p-nitrophenol-UDP-glucuronyltransferase, all of which are typically induced by 3-methylcholanthrene. Effects on body weight gains were similar for all treatments and although less than control they were not statistically different. Only the thymic weights of animals treated with the reconstituted mixture were significantly less than controls. Therefore, it may be concluded that these effects of Firemaster (FF-1 or BP-6) must be due to the effects of the congeners studied, and that no other component in these mixtures, a brominated biphenyl or otherwise, may significantly contribute to these effects.