In vitro contractile response of human myometrium to oxytocin, PGF2alpha, bradykinin and ET-1

The imbalance in the sex hormones levels is the limited factor which induces disturbances in the uterus function and elevates uterine contractile activity. The aim of our study was to evaluate and compare the direct contractile responsiveness of myometrium to the effects of uterotonic agents--oxytocin, PG2alpha, ET-1, and bradykinin--in the strips of human non-pregnant myometrium during different phases of menstrual cycle. Reactivity of human myometrial strips, obtained from the pre-menopausal woman undergoing total hysterectomy for benign gynaecological indications such as leiomyomas, was evaluated in vitro. Our results showed an increased reactivity of myometrium to contractile mediators during follicular phase of the cycle. Our findings support the idea that estrogens might have a positive influence on the expression of various types of receptors (FP, OTR, BK2R and ET(A)R) and thus promote the contractility in response to uterotonic agents. On the contrary, minimal myometrial response to oxytocin, PG2alpha, ET-1, and bradykinin were observed during luteal phase when progesterone levels are increased. Our results indicate that the contractile activity of myometrium is mostly influenced by changes in sex steroid hormones during menstrual cycle. In future, this experimental model can be used for the study of mechanism regulating myometrial smooth muscle reactivity and its pharmacological modulation (Fig. 4, Ref. 20). Full Text (Free, PDF) www.bmj.sk.