Rat hepatic microsomal cytochrome(s) P-450 induced by polybrominated biphenyls.
Various parameters have been measured in order to characterize the type of cytochrome(s) P-450 induced by a single ip injection of polybrominated biphenyls (PBB's), 150 mg/kg, given to female rats. The ratio of the 427/455-nm peaks in the microsomal ethylisocyanide difference spectra showed a gradual increase with time after treatment with PBB's. Inhibition studies of aryl hydrocarbon hydroxylase and ethoxycoumarin O-de-ethylase and alpha-naphthoflavone and metyrapone also showed changes in the qualitative nature of these enzymes after treatment with PBB's. Both the high- and low-affinity KM values for ethoxycoumarin O-de-ethylase decreased in magnitude from 0.240 and 0.083 micrometer at 24 hr to 0.188 and 0.042 micrometer, respectively, at 192 hr after treatment with PBB's. Sodium dodecyl sulfate-gel electrophoresis failed to demonstrate a 3-methylcholanthrene-like pattern of hemoprotein at any time after treatment with PBB's. We conclude that while PBB's have some of the properties of a mixed inducer they do not have all of the properties of both phenobarbital and 3-methylcholanthrene, and the PBB's may represent a new class of inducing agents.
D000818:Animals; D001579:Benzopyrene Hydroxylase / Q000037:antagonists & inhibitors; D001713:Biphenyl Compounds / Q000494:pharmacology*; D003374:Coumarins / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis*; D003640:Dealkylation; D004591:Electrophoresis, Polyacrylamide Gel; D004790:Enzyme Induction / Q000187:drug effects; D005019:Ethyl Ethers; D005260:Female; D066298:In Vitro Techniques; D007700:Kinetics; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D010088:Oxidoreductases / Q000378:metabolism; D011075:Polybrominated Biphenyls / Q000494:pharmacology*; D051381:Rats; D013053:Spectrophotometry; D013997:Time Factors
D001713:Biphenyl Compounds; D003374:Coumarins; D005019:Ethyl Ethers; D011075:Polybrominated Biphenyls; D003577:Cytochrome P-450 Enzyme System; D010088:Oxidoreductases; D001579:Benzopyrene Hydroxylase