Effects of erythropoietin on spontaneous and oxytocin induced myometrial contractions in the nonpregnant rat.

OBJECTIVE: Erythropoietin (EPO) is a glycoprotein hormone that regulates erythropoiesis. EPO activity has also been detected in a variety of tissue including the nervous system, and female and male reproductive organs. It has been shown that EPO causes relaxation in vascular smooth muscle. In the present study, we have investigated effects of EPO on spontaneous and oxytocin-induced contractions of non-pregnant rat myometrium.

MATERIALS AND METHODS: Myometrial stripes were obtained from adult Wistar rats at the oestrous stage. The samples were placed in an isolated organ chamber under physiological conditions and 1 g passive tension. Epoetin beta (rEPO) was added cumulatively at 0.1, 1 and 10 IU/ml concentrations to the myometrial samples showing regular spontaneous contractions for periods of 30 min. Frequency and amplitude of contractions were electrophysiologically recorded and analyzed by using a BIOPAC data acquisition system.

RESULTS: rEPO inhibited both area under curve and frequency of spontaneous contractions (ANOVA, n1, 2 = 9, f1 = 20.938, f2 = 20.492, p1,2 = 0.000). The inhibitory effect was insignificant at 0.1 mIU/ml rEPO level (Tukey HSD, p1 = 0.051, p2 = 0.581). In the oxytocin treated myometrial samples, a single dose of 1 IU/ml rEPO was studied. The area under curve and frequency values of these samples were inhibited by rEPO (Student's t-test, n = 9, t1 = 4.776, p1 = 0.000; t2 = 2.835, p2 = 0.012, respectively).

CONCLUSIONS: rEPO inhibited spontaneous and oxytocin-induced rat myometrial contractions at 1 and 10 IU/ml concentrations. It appeared that the effect was dose-dependent.