Te Efects of Sex Steroids on Human Umbilical A~rteryrand Vein

OBJECTIVE: To define the vascular actions of selected sex steroids on human umbilical artery and vein and to determine whether there are any gender-specific differences in vasorelaxation between umbilical cord vessels of male and female fetuses. METHODS: Segments of umbilical artery (n = 12) and umbilical vein (n = 8) from male andfemale fetuses were suspended in organ baths of Krebs solution for isometric tension recording. The vessels were contracted using 60 mMpotassium chloridefollowed by exposure to increasing concentrations (10 7 to 10-4 M) of sex steroid hormones (estradiol-1713, estriol, estrone, testosterone, and progesterone). A specific estrogen receptor antagonist (ICI 164,384) was used to attempt to block the estradiol effect. Changes in tension were recorded. RESULTS: Of the agents tested, estradiol- 1 7f had the greatest effect (25-29 % relaxation at 10-4 M concentration), which was uninhibited by a specific receptor antagonist. The other steroids tested had no significant effect, even at 10-4 M concentration. The umbilical artery is slightly more sensitive to the effects of estradiol than the umbilical vein. There were no gender-specific differences noted in either artery or vein harvested from male orfemale fetuses. CONCLUSION: Estradiol- 1 7f in supraphysiologic concentrations has a non-receptor-mediated vasore-laxation effect on human umbilical blood vessels. (J Soc Gynecol Invest 1999;6:27-31) Copyright © 1999 by the Society for Gynecologic Investigation