Specific transfer of hydrogen from estradiol to progesterone as a regulating principle for progesterone metabolism in the liver of the female rat.

20a-Hydroxy-A4-pregnen-3-one-20p-3H can be detected after incubation of progesterone and estradiol-17a-3H with slices of female rat liver and rat ovaries, which proves the transfer of hydrogen from estradiol to progesterone. While 20oc-hydroxy-A4-pregnen-3-one is found only in very small amounts after incubation of progesterone with female rat liver slices the reduction at CzO increases 20-fold if estradiol is also added to the incubation mixture. A regulating effect of estradiol on the progesterone metabolism in female rat liver and rat ovaries is discussed.