A comparison of the in vitro metabolism of estrone, estradiol-17 beta and estrone-3-sulfate by the livers of young virgin female, pregnant and female fetal guinea-pigs.

The metabolism, in vitro, of [3H]-estrone, [3H]-estradiol-17 beta and [13H]-estrone-3-sulfate by the livers of pregnant, young virgin female and female fetus guinea-pigs has been compared using 900 g supernatants and microsomes. The ability of the guinea-pig livers to synthesize polyhydroxylated estrogens has been fo-nd to be small. The major metabolites isolated were unconjugated estrone and estradiol-17 beta or their glucuronides. The percentage of sulfates was lower after incubations with [3H]-estrone than with [3H]-estradiol-17 beta. A kinetic study with microsomes has shown a direct conversin of estrone-sulfate to estradiol sulfate. Fetal microsomes have been found to exhibit a more active hydrogenation of estrone to estradiol-17 beta than microsomes from young female or pregnant animals.