Contractile effects of endothelins on isolated human ureter.

The aim of our study was to investigate mechanism of action of endothelins 1, 2 and 3 on spontaneous activity, tone and intraluminal pressure of human ureter. Both longitudinal tension and intraluminal pressure were recorded from the isolated segments of proximal human ureter. Endothelins 1, 2 and 3 (5.35x10(-11) M - 5.05x10(-8) M) produced concentration-dependent tonic contraction and sustained increase in intraluminal pressure of isolated preparations of human ureter. Endothelins 1 and 3 produced also concentration-dependent inhibition of spontaneous, phasic contractions of the isolated preparations. Selective antagonist of ET(A) receptors BQ123 and selective antagonist of ET(B) receptors BQ788 produced significant inhibition of endothelin-1-induced tonic contraction (pA(2)=8.80 and 6.55, respectively) and increase in intraluminal pressure (pA(2)=8.68 and 7.02, respectively), while they did not affect endothelin-1-induced inhibition of spontaneous activity. Endothelin 1 produces increase in tone and intraluminal pressure of isolated human ureter acting on both ET(A) and ET(B) receptors, the first one being functionally more important. Only endothelins 1 and 3 inhibit spontaneous, phasic activity of human ureter, but this effect was not blocked by selective antagonists of ET(A) and ET(B) receptors.

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.