F. Wiebel
Jun 1, 1975
Citations
0
Influential Citations
72
Citations
Quality indicators
Journal
Archives of biochemistry and biophysics
Abstract
Abstract The 3-, 6-, and 9-monohydroxybenzo(a)pyrenes are metabolized by microsomes from rat liver in vitro . The metabolism of 3-hydroxybenzo(a)pyrene requires the presence of NADPH and is inhibited by carbon monoxide, suggesting that the reaction is mediated by a microsomal mixed-function oxygenase. The metabolic activity can be induced by in vivo treatment with 3-methylcholanthrene. 7,8-Benzoflavone strongly inhibits the induced activity but has little effect on the constitutive enzyme. The inducibility and inhibition characteristics, as well as the metabolic rate of the conversion of 3-hydroxybenzo(a)pyrene, closely resemble those of the oxidative metabolism of benzo(a)pyrene. The microsomal NADPH-dependent metabolism of [3H]3-hydroxybenzo(a)pyrene leads to the formation of a number of products of which a major fraction cochromatographs with the 3,6-quinone of benzo(a)pyrene. In mammalian cell cultures 3-hydroxybenzo(a)pyrene is converted by a mechanism different from that in hepatic microsomes. The disappearance of the phenol in cultures of hamster embryo cells is independent of the action of inducers or inhibitors of the aryl hydrocarbon hydroxylases and also occurs in the mouse L-cell line, A9, which lacks detectable aryl hydrocarbon hydroxylase activity. In A9 cells, [3H]3-hydroxybenzo(a)pyrene is largely converted to water soluble derivatives.