Reproductive sciences
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Reproductive sciences · Mar 2010
Comparative StudyOxytocin pretreatment of pregnant rat myometrium reduces the efficacy of oxytocin but not of ergonovine maleate or prostaglandin F 2 alpha.
Oxytocin receptors (OTRs) in both human and rat myometrial cells are desensitized by exposure to oxytocin, thereby reducing the ability of the cells to respond to the subsequent administration of oxytocin. However, it is unclear if this desensitization phenomenon is confined to oxytocin, or extends to other uterotonic agents such as ergonovine or prostaglandin F(2 alpha) (PGF(2 alpha)). We compared the in vitro contractile responses of myometrial samples from pregnant Wistar rats at 20 to 22 days of gestation. ⋯ However, oxytocin produced superior contractions in the control and oxytocin-pretreated myometrium compared to either ergonovine or PGF(2 alpha). Our study shows that the uterotonic effects of ergonovine and PGF(2 alpha) are not affected by the phenomenon of oxytocin desensitization in pregnant rat myometrium. However, oxytocin, despite the phenomenon of desensitization, provides superior uterine contractions when compared to ergonovine or PGF(2 alpha).