Abstract
Uridine diphosphate glucuronate glucuronyltransferase (UDPGT) activity was measured in hepatic microsomes with 14C-estrone and 17β-14C-estradiol as substrates. The apparent Km values for the conjugation of estrone and estradiol by rat liver microsomes were 1.78 ± 0.56 x 10-5 M and 2.53 ± 0.94 x 10-5 M, respectively (mean of 20 determinations ± SD). The conjugation of estrogens was inhibited by morphine, p-hydroxyamphetamine, SKF 525-A, and both the demethylated and hydroxylated metabolites of chlorpromazine. Phenobarbital, 3-methylcholanthrene, and 3,4-benzpyrene increased the conjugation of the estrogens per g of liver but not the specific activity of UDPGT (nanomoles per mg of microsomal protein). Pretreatment of rats with morphine, chlorpromazine, and amphetamine increased the specific activity of the transferase for the conjugation of estrogens.
Footnotes
- Received July 19, 1974.
- Copyright © 1974 by The American Society for Pharmacology and Experimental Therapeutics
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THE INTERACTION OF FOREIGN CHEMICAL COMPOUNDS WITH THE GLUCURONIDATION OF ESTROGENS IN VITRO
