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Endothelin‐1 receptors in the human myometrium: evidence for different binding properties in post‐menopausal as compared to premenopausal and pregnant women
Author(s) -
Schiff Eyal,
BenBaruch Gilad,
Galron Ronit,
Mashiach Shlomo,
Sokolovsky Mordechai
Publication year - 1993
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.1993.tb01012.x
Subject(s) - myometrium , endocrinology , medicine , luteal phase , receptor , endothelin receptor , endothelin 1 , follicular phase , menopause , menstrual cycle , ovary , biology , uterus , hormone
Summary OBJECTIVE We investigated the binding properties of the endothelin receptors in the human myometrium in clinical situations associated with different ovarian steroid levels. SUBJECTS AND METHODS Binding properties of the endothelin receptors were studied in myometrial membranes from post‐menopausal women ( n = 12), myomatous premenopausal women ( n = 14) and pregnant women ( n = 14), using 125 I‐labelled endothelin‐1. RESULTS The mean (SD) maximal receptor density ( B max ) was significantly higher in samples from premenopausal and pregnant women than from post‐menopausal women (983 ± 196, 1116 ± 201 and 490 ± 145 pmol/g protein, respectively). Receptor affinity ( K d ) did not differ significantly between these groups. Among the pregnant women, mean B max and K d values were similar in those who electively underwent Caesarean section prior to the onset of labour and those operated on during the second stage of spontaneous labour. Binding properties of myometrial membranes of either pre or post‐menopausal women were unaffected by the presence of high levels of beta‐oestradiol or progesterone in the medium. Among samples of premenopausal women, no significant difference was found in binding properties between those operated on either during mid‐follicular phase or during mid‐luteal phase. CONCLUSIONS In clinical situations associated with relatively high levels of ovarian steroids, the density of endothelin receptors in the myometrium is higher than in situations associated with low ovarian steroid level. Ovarian steroids may exert their influence via the production of other mediators. Changes in density of the endothelin receptor, induced by change in ovarian steroids activity, might play a role in the regulation of myometrial contractility.