The contractile effects of endothelins on isolated isthmic segment of human oviduct at the luteal phase of the menstrual cycle.

The purpose of this study was to investigate the effects of endothelins (ET) 1, 2 and 3 on isolated isthmic segments of the human oviduct at the luteal phase of menstrual cycle. Fallopian tubes were taken from 21 patients and the isthmic segments were mounted in an organ bath longitudinally. Tension of the isolated preparations was recorded with an isometric transducer. ET-1 and ET-2 triggered concentration-dependent tonic contractions of the isolated isthmic segment and inhibited rhythmic activity, while ET-3 caused no effect. Furthermore, the selective ET(A) antagonist BQ-123 and the selective ET(B) antagonist BQ-788 inhibited the ET-1 effects on both tone and spontaneous rhythmic contractions. These results suggested that during the luteal phase of the menstrual cycle, both ET(A) and ET(B) receptors participate in contractile effects of endothelins on isthmic segment of fallopian tubes, probably regulating the length of time the oocyte remains in the oviduct ampulla.