TRANSFORMATION OF ESTRONE, ESTRADIOL, AND ESTRONE SULFATE IN UTERINE AND VAGINAL ISOLATED CELLS OF FETAL GUINEA-PIG - EFFECT OF VARIOUS ANTIESTROGENS IN THE CONVERSION OF ESTRONE SULFATE TO ESTRADIOL

The metabolism of physiological concentrations (5 x 10(-9) M) of [H-3] estrone (E1), [H-3]estradiol (E2), and [H-3]estrone sulfate (E1S) was studied in isolated fetal uterine and vaginal cells of guinea pigs in culture. After 24 hours of incubation in both cells, a large percentag e (40-60%) of E1 is converted to E2; however, after incubation of E2, most of the radioactive material (45-65%) corresponds to unchanged E2. Similarly, in the incubation medium the concentration of E2 is signif icantly higher related to E1 after incubation with E1 or E2. An intens e sulfotransferase activity is found for both estrogens, whereas in th e culture medium the respective sulfates represent 27-45% of the total radioactive material after incubation with the uterine cells and 15-2 4% for the vaginal cells. Using E1S, significant hydrolysis is observe d in both cells and the analysis of the freed radioactive material ind icated a high percentage in E2 (66% in the uterine cells and 71% in th e vaginal cells). The conversion of E1S to E2 was strongly decreased b y the antiestrogens: tamoxifen, 4-hydroxy-tamoxifen, and ICI 164,384. The inhibitory effect in relation to the incubation with E1S only was 43-66% in the uterine cells and 50-85% in the vaginal cells. The prese nt data suggest that estrogen sulfates can play an important biologica l role in the target tissues of the fetus, and that the enzymatic mech anisms of the bioavailability of E2 for the biological responses of th e hormone can be operated in the target tissue itself.