Ovarian Hormones · Progesterone
Haukkamaa M, 1984 · J Steroid Biochem
Microsomal membranes sedimented at 40 000 g were prepared from human myometrium samples. The progesterone binding properties of microsomal suspensions were determined by incubating microsomes and [3H]progesterone at 4 degrees C. Dextran-coated charcoal was used for the separation of bound and free steroids. Membrane-associated progesterone binding sites of high affinity were identified in microsomes prepared from pregnant and nonpregnant uteri. The binding was saturable (Kd approximately 4 X 10(-9) M, concentration of binding sites 400-900 fmol/mg microsomal protein) and specific for natural progesterone. Of 21 steroids tested only 21-hydroxy-4-pregnene-3,20-dione, 17 alpha-hydroxyprogesterone and testosterone showed moderate competition against progesterone with relative affinities between 7.0-20.0% (R.A. of progesterone 100%). 5 alpha-Dihydroprogesterone and 5 alpha-dihydrotestosterone showed weak cross reaction (relative affinities 2.5 and 2.0%, respectively). Corticosteroids, estrogens and the 5 synthetic progestins tested showed only weak competition with relative affinities lower than 1.0%. These microsomal progesterone binding sites of high affinity and limited capacity resemble steroid hormone receptors but they are different from the soluble cytosolic progesterone receptor of human uterus in terms of steroid specificity. The physiological function of this microsomal progesterone receptor is unknown.
Ovarian Hormones · Estrogen
Tulchinsky D et al., 1972 · Am J Obstet Gynecol
To describe normal relationships between the various plasma unconjugated estrogens and progesterone during the second half of human pregnancy, the plasma concentrations of progesterone, 17-hydroxyprogesterone (17-OHP), and unconjugated estrone (E1), estradiol (E2), and estriol (E3) were measured in 126-310 normal women. Progesterone and unconjugated E1, E2, and E3 increased gradually throughout later pregnancy; 17-OHP increased only after the thirty-third week. At term the mean value of progesterone was 9 times higher than that 17-OHP. Throughout pregnancy the mean value of E2 was higher than that of E1 or E3. During the second half of pregnancy the ratios of progesterone to estradiol and estriol and of estradiol to estriol remained unchanged, indicating no preferential increase of plasma concentration of maternal or fetal hormones.
Ovarian Hormones · Progesterone
Tulchinsky D et al., 1975 · Am J Obstet Gynecol
The plasma concentration of progesterone (P) has been measured by radioimmunoassay in maternal peripheral vein (M.P.V.) at early pregnancy and in M.P.V. umbilical artery (U.A.) and umbilical vein (U.V.) at term pregnancy. In early preganacy marked hour-to-hour fluctuation of plasma progesterone was noted. At term pregnancy plasma P levels of U.V. were higher than those of U.A. and the umbilical venous arterial differences of plasma P did not differ between male and femal fetuses. Administration of hydrocortisone and ACTH to patients scheduled to undergo cesarean section had no effect on M.P.V., U.A., and U.V. plasma P concentration. On the basis of the differences between U.V. and U.A. plasma P concentrations and reported umbilical flow it was estimated that the secretion rate of P into the fetal circulation is approximately 23 mg. per 24 hr. and would amount to approximately 10 per cent of the reported total daily production rate of P at term pregnancy. The fraction of P which is unbound to the plasma proteins was estimeated by equilibrium dialysis at 37 degrees C. The per cent unbound P in M.P.V. plasma of pregnant patients at term was not different from that of nonpregnant patients but was 40 per cent lower than that in umbilical cord plasma (P LESS THAN 0.01), and the ratio between the concentrations of unbound P and estradiol in M.P.V. increased as pregnancy progressed. Plasma P in re-eclamptic patients who subsequently sustained intrauterine fetal death had no value in assessing placental function.
Ovarian Hormones · Progesterone
Johansson ED, 1969 · Acta Endocrinol (Copenh)
Plasma levels of progesterone* were measured during normal human pregnancy by a sensitive and rapid competitive protein binding technique. During the first half of gestation 440 determinations in 321 women and in the second half of gestation, 209 determinations in 160 women were performed.
The average plasma level of progesterone in the 5th week of gestation was 24.8 ± 7.3 (s) ng/ml which is above the normal range of the luteal plateau of the menstrual cycle (10–20 ng/ml). Between the 5th and the 9th week of gestation the plasma concentration decreased significantly. From the 9th to the 32nd week of gestation the plasma level of progesterone increased from 16.7 ± 7.4 (s) to 125.2 ± 37.9 (s) ng/ml. During the last 8 weeks of gestation the plasma levels of progesterone did not show any significant rise. One woman was followed up from the day of ovulation to the 8th week of gestation. An increase in progesterone levels was observed about 10 days after ovulation. Morning samples of progesterone, which were taken before the 20th week of gestation, when the woman was still in bed, were found to be somewhat higher than levels found during the remainder of the day.
Progesterone concentrations in a few abnormal pregnancies are also reported.
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