Falkay G, Kovács L
J Perinat Med. 1986;14(2):109-13. doi: 10.1515/jpme.1986.14.2.109.
The beta-adrenoreceptor antagonist [3H]-dihydroalprenolol (DHA) has been used to label adrenoreceptors in membranes from human pregnant myometrium and placenta. Six tocolytic drugs were tested for their ability to bind to the beta-adrenergic receptor of placental and myometrial membranes. Tocolytic agents competed with [3H]-DHA binding in the following order of potency: clenbuterol greater than fenoterol greater than ritodrine greater than isoxsuprine greater than orciprenaline greater than terbutaline. All drugs competed for [3H]-DHA binding sites with HILL coefficients greater than unity indicating heterogeneity of binding. In general, binding of beta-adrenoreceptor agonists was weaker in myometrium than in placenta homogenates. According to our results it is very likely that the placenta may play an important role in the pharmacological mechanism of tocolytic agents in inhibitory of premature labor.
β-肾上腺素能受体拮抗剂[³H]-二氢烯丙洛尔（DHA）已被用于标记人妊娠子宫肌层和胎盘膜中的肾上腺素能受体。测试了六种宫缩抑制剂与胎盘和子宫肌层膜β-肾上腺素能受体的结合能力。宫缩抑制剂与[³H]-DHA结合的竞争效力顺序如下：克仑特罗＞非诺特罗＞利托君＞异克舒令＞奥西那林＞特布他林。所有药物与[³H]-DHA结合位点竞争时的希尔系数均大于1，表明结合存在异质性。一般来说，β-肾上腺素能受体激动剂在子宫肌层中的结合比在胎盘匀浆中更弱。根据我们的结果，胎盘很可能在宫缩抑制剂抑制早产的药理机制中起重要作用。
