Izumi H, Byam-Smith M, Garfield R E
Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston 77555-1062, USA.
Eur J Pharmacol. 1995 May 24;278(3):187-94. doi: 10.1016/0014-2999(95)00089-4.
The mechanical effects of KCl, oxytocin and endothelin-1 on pregnant rat myometrium were examined using intact strips and beta-escin-treated skinned strips. Myometrial tissues from delivering rats were more sensitive to 10.7 mM K+ compared to mid and late gestation. Maximum contractions induced by K+ were obtained at concentrations of 118 mM at mid and late gestation and during delivery. The maximum amplitude of contractions induced by oxytocin and endothelin-1 compared to the 118 mM K(+)-induced contraction increased during the progress of gestation. Maximum contractions induced by oxytocin and endothelin-1 were greater than those induced by 118 mM K+ at delivery, and maximum contractions by oxytocin were larger than those by endothelin-1 during delivery. In 10 microM nifedipine and Ca(2+)-free (containing 2 mM EGTA) solutions, 118 mM K+ contractions were completely abolished; however, both oxytocin and endothelin-1 produced contractions. In Ca(2+)-free solutions, contractions by oxytocin were larger than those by endothelin-1. In skinned myometrial strips, guanosine 5'-O-thiotriphosphate (GTP, 1 microM-1 mM), guanosine 5'-O-(gamma-thiotriphosphate) (GTP gamma S, 0.1-100 microM) and oxytocin (1 nM-0.1 microM) with 10 microM GTP, but not endothelin-1 with 10 microM GTP increased Ca2+ sensitivity of contractile force.(ABSTRACT TRUNCATED AT 250 WORDS)
使用完整的肌条和经β-七叶皂苷处理的去皮肌条，研究了氯化钾、催产素和内皮素-1对妊娠大鼠子宫肌层的机械效应。与妊娠中期和晚期相比，分娩大鼠的子宫肌层组织对10.7 mM钾离子更敏感。在妊娠中期、晚期和分娩期间，钾离子浓度为118 mM时可诱导最大收缩。与118 mM钾离子诱导的收缩相比，催产素和内皮素-1诱导的最大收缩幅度在妊娠过程中增加。在分娩时，催产素和内皮素-1诱导的最大收缩大于118 mM钾离子诱导的收缩，且分娩时催产素诱导的最大收缩大于内皮素-1诱导的收缩。在10 microM硝苯地平和无钙（含2 mM乙二醇双四乙酸）溶液中，118 mM钾离子诱导的收缩完全被消除；然而，催产素和内皮素-1均可引起收缩。在无钙溶液中，催产素引起的收缩大于内皮素-1引起的收缩。在去皮子宫肌条中，鸟苷5'-O-硫代三磷酸（GTP，1 microM - 1 mM）、鸟苷5'-O-（γ-硫代三磷酸）（GTPγS，0.1 - 100 microM）以及与10 microM GTP共同作用的催产素（1 nM - 0.1 microM）可增加收缩力的钙敏感性，但与10 microM GTP共同作用的内皮素-1则不会。（摘要截断于250字）
