Downing S J, McIlwrath A, Hollingsworth M
Department of Physiological Sciences, Medical School, Manchester University, UK.
J Reprod Fertil. 1992 Nov;96(2):857-63. doi: 10.1530/jrf.0.0960857.
The relationship between relaxant actions of relaxin in the uterus and changes in uterine cAMP concentrations was assessed in anaesthetized bilaterally ovariectomized nonpregnant rats. Relaxin i.v. bolus (5 micrograms kg-1) did not change cAMP concentrations but inhibited uterine contractions with rapid onset. Uterine contractions were significantly reduced by 30-70% for 60 min. Relaxin (50 micrograms kg-1) produced a short-lived (up to 5 min) and small (up to 3.2-fold) increase in cAMP concentrations plus a marked (90%) and prolonged inhibition of uterine contractions (70-90% over 60 min). Salbutamol (an agonist at beta 2-adrenoceptors, 100 and 500 micrograms kg-1) produced a similar degree and time course of inhibition of uterine contractions to that of relaxin but a more marked (19-fold) increase in cAMP concentrations. Glibenclamide, a blocker of ATP-sensitive potassium channels, which has been shown to antagonize relaxin as a uterine relaxant, did not prevent the relaxin-induced rise in cAMP concentrations. It is suggested that the uterine relaxant action of relaxin may not result from an increase in uterine cAMP concentrations.
在麻醉的双侧卵巢切除的未孕大鼠中，评估了松弛素在子宫中的松弛作用与子宫环磷酸腺苷（cAMP）浓度变化之间的关系。静脉推注松弛素（5微克/千克）不会改变cAMP浓度，但会迅速抑制子宫收缩。子宫收缩在60分钟内显著降低了30%-70%。松弛素（50微克/千克）使cAMP浓度短暂升高（持续5分钟）且幅度较小（最高3.2倍），同时对子宫收缩产生显著（90%）且持久的抑制作用（60分钟内抑制70%-90%）。沙丁胺醇（一种β2肾上腺素能受体激动剂，100和500微克/千克）对子宫收缩的抑制程度和时间进程与松弛素相似，但使cAMP浓度升高更为显著（19倍）。格列本脲是一种ATP敏感性钾通道阻滞剂，已被证明可拮抗松弛素的子宫松弛作用，但它并不能阻止松弛素诱导的cAMP浓度升高。提示松弛素的子宫松弛作用可能不是由子宫cAMP浓度升高引起的。
