Binding of progesterone by human uterine cytosol.

Progesterone binding by 100,000 X g cytosols of human myometria from patients undergoing hysterectomy for various reasons was assayed using equilibrium dialysis or DEAE-cellulose filtration. The estimates of high-affinity porgesterone binding obtained by both techniques showed a significant correlation. Dialysis and filtration assays with cortisol competing with [3H]progesterone for binding indicated that the specific progesterone binding by the cytosols was the result of progesterone interaction with two high-affinity constitutents. Myometrial cytosols from tissues under progestin stimulation (secretory endometrium or pregnancy) had low concentrations of progestin binders. Cytosols from uteri with atrophic endometrium showed consistently high concentrations of progestin binders and those tissues under estrogen stimulation (proliferative endometrium or hyperplasia) and variable binder concentrations. No differences were detected between grouped observtions classified into 10 clinical categories. The DEAE-cellulose filtration is an effective method for evaluating progesterone binding which uses well-established statistical techniques and requires less tissue, less time for incubations, and fewer points for reliable analysis than does equilibrium dialysis.