Metabolites of estradiol-17beta in guinea pig uterus late in pregnancy.

The metabolism of estradiol-17beta by the guinea pig uterus late in pregnancy was studied in vivo and in vitro. Whole uteri were examined for estrogen metabolites one hour following an intravenous injection of [3H]-estradiol-17beta or uterine sections were examined after incubation for one hour at 37 degrees C in medium containing [3H]-estradiol-17beta. In both instances uterine tissue metabolized estradiol-17beta to five products; estrone, estrone-3-sulfate, 17beta-estradiol-3-sulfate, estrone-3-glucuronide and 17beta-estradiol-3-glucuronide. Of the total radioactive products 11-43% were glucuronides, 17-26% were sulfates and 4-17% was estrone. These results indicate that the guinea pig uterus actively transforms estradiol-17beta into glucuronides and sulfates late in pregnancy.