In VivoUptake and Subcellular Distribution of Tritium- Labeled Estrogens in Human Endometrium, Myometrium, and Vagina

Uptake, retention, and subcellular distribution of 17β-estradiol (E2), estrone (E1), and estriol (E3) in endometrial, myometrial, and vaginal tissue in 18 normal postmenopausal women under physiological conditions were studied by giving [3H]E2, [3H]Ei, or [3H]E3 in subphysiological doses by continuous infusion lasting 12 h before hysterectomy. Endometrial, myometrial, and vaginal tissues from each woman were separated into five cellular fractions: two cytosol fractions (free estrogen fraction and specifically bound fraction) and three nuclear fractions. The results show an accumulation of [3H]E2 in the target tissue after [3H]E2 and [3H]Ei infusions; we found an approximately 30 times higher [3H]E2 concentration after [3H]E2 infusion in endometrium (disintegrations per min/ g) than in plasma (disintegrations per min/ml), 20 times higher in myometrium, and 10 times higher in vaginal tissue. The corresponding [3H]Ei tissue to plasma ratios were 7, 4, and 6, respectively, for endometrium, myometrium, and vag...