Laursen M, Bodelsson G, Stjernquist M
Department of Obstetrics and Gynaecology, University Hospital, Malmö, Sweden.
Eur J Pharmacol. 1998 Dec 4;362(2-3):167-72. doi: 10.1016/s0014-2999(98)00738-9.
The receptors mediating smooth muscle response to endothelin-1 and sarafotoxin S6b in the human umbilical artery were investigated in vitro. Both agonists induced contractions that were unaffected by the endothelin ET(B) receptor antagonist BQ 788 (10(-9), 10(-8), 10(-7) M). The non-selective endothelin ET(A/B) receptor antagonist PD 142893 (10(-7) M) decreased the contraction induced by endothelin-1. PD 142893 (10(-9) M) enhanced the contraction induced by sarafotoxin S6b whereas higher concentrations had no effect. Removing the endothelium did not affect the antagonising action of PD 142893 on endothelin-1-induced contractions while the enhancement of the sarafotoxin S6b-induced contraction was abolished. Sarafotoxin S6b induced relaxation in segments precontracted by 5-hydroxytryptamine and exposed to the endothelin ET(A) receptor antagonist BQ 123 (10(-7) M) and PD 142893 (10(-9) M) abolished this relaxation. These endothelial receptors seem neither to be classical endothelin ET(A) nor endothelin ET(B) receptors and they are not activated by endothelin-1.
体外研究了介导人脐动脉平滑肌对内皮素 -1 和芋螺毒素 S6b 反应的受体。两种激动剂均诱导收缩，且不受内皮素 ET(B) 受体拮抗剂 BQ 788（10(-9)、10(-8)、10(-7) M）的影响。非选择性内皮素 ET(A/B) 受体拮抗剂 PD 142893（10(-7) M）可减弱内皮素 -1 诱导的收缩。PD 142893（10(-9) M）增强了芋螺毒素 S6b 诱导的收缩，而更高浓度则无作用。去除内皮并不影响 PD 142893 对内皮素 -1 诱导收缩的拮抗作用，而芋螺毒素 S6b 诱导收缩的增强作用则被消除。芋螺毒素 S6b 在由 5 - 羟色胺预收缩并暴露于内皮素 ET(A) 受体拮抗剂 BQ 123（10(-7) M）的节段中诱导舒张，而 PD 142893（10(-9) M）消除了这种舒张。这些内皮受体似乎既不是经典的内皮素 ET(A) 受体也不是内皮素 ET(B) 受体，且它们不会被内皮素 -1 激活。
