EVIDENCE OF INTERPLAY BETWEEN PLASMA ENDOTHELIN-1 AND 17-BETA-ESTRADIOL IN REGULATION OF UTERINE BLOOD-FLOW AND ENDOMETRIAL GROWTH IN INFERTILE WOMEN

Objective: To determine the effects of gonadotropin-induced ovarian st imulation on the plasma levels of endothelin-1 as well as on uterine b lood flow and endometrial thickness. Design: Controlled cross-over cli nical study. Setting: Academic research environment. Patient(s): Eight een volunteer infertile women (31.4 +/- 2.5 years, mean +/- SE) partic ipating in an IVF-ET program. Intervention(s): Transvaginal Doppler ul trasound was performed and blood samples were collected 4 days after t he LH surge in a spontaneous cycle and 4 days after hCG administration in a subsequent gonadotropin-stimulated cycle. Main Outcome Measure(s ): Plasma levels of E-2, P, and endothelin-1; uterine artery pulsatili ty index; and endometrial thickness. Result(s): Stimulated cycles were associated with significantly higher E-2 levels (101.0 +/- 10.2 versu s 723.5 +/- 57.3 pg/mL [conversion Factor to SI unit, 3.671]; spontane ous versus stimulated), thicker endometrium (9.2 +/- 2.5 versus 11.4 /- 2.9 mm), and lower endothelin-1 levels (2.5 +/- 0.1 versus 2.1 +/- 0.1 pg/mL [conversion factor to SI unit, 0.4]) and pulsatility index ( 3.22 +/- 0.12 versus 2.63 +/- 0.08) than spontaneous cycles. Endotheli n-1 correlated negatively with E-2 (r = -0.38), but not with P or puls atility index. Differences in endothelin-1 and endometrial thickness b etween spontaneous and stimulated cycles correlated negatively (r = -0 .56) with each other. Conclusion: Our results suggest an inhibitory ro le for E-2 in the release of endothelin-1, which could be a factor in the regulation of uterine and endometrial blood flow. (C) 1997 by Amer ican Society for Reproductive Medicine.