title: A comparison of the activities of aryl hydrocarbon monooxygenase in liver microsomes from mice of different strains during prolonged 3,4-benzo(a)pyrene administration.
abstract: The content and activity of the components of liver microsomal aryl hydrocarbon monooxygenase system change biphasically during long-term 3,4-benzo(a)pyrene administration of C57BL/6  mice as well as to (C57BL/6 X DBA/2)F1 hybrids. The first activity peak (4--14 days) is associated with the induction of aryl hydrocarbon monooxygenase by 3,4-benzo(a)pyrene; the second peak (70--84 days) is related to noninductive mechanism. In DBA/2 mice, the second peak is absent while the slight increase in aryl hydrocarbon monooxygenase activity observed on days 14--28 indicates the aberrant inductive capacity of 3,4-benzo(a)pyrene under its prolonged administration. It is suggested that the weak sensitivity to the blastogenesis caused by 3,4-benzo(a)pyrene observed in C57BL/6 mice and in (C57BL/6 X DBA/2)F1 hybrids is due to the high level of liver aryl hydrocarbon monooxygenase activity at the time of tumor appearance.
mesh_terms: D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism*; D001580:Benzopyrenes / Q000494:pharmacology*; D003580:Cytochromes / Q000378:metabolism; D004790:Enzyme Induction; D007700:Kinetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008862:Microsomes, Liver / Q000201:enzymology*; D009369:Neoplasms / Q000139:chemically induced; D051381:Rats; D013045:Species Specificity; D013997:Time Factors
chemical_list: D001580:Benzopyrenes; D003580:Cytochromes; D001189:Aryl Hydrocarbon Hydroxylases