Kocan L H, MacLusky N J, Lye S J
Division of Perinatology, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.
Am J Obstet Gynecol. 1993 Mar;168(3 Pt 1):961-8. doi: 10.1016/s0002-9378(12)90853-4.
The purpose of our study was to determine the susceptibility of the myometrium to beta-adrenergic agonist-induced desensitization and to determine the ability of dexamethasone to prevent this homologous desensitization.
Myometrial tissue was collected from nonpregnant, pregnant, and postpartum rats (n > or = 6) 12 hours after injection of either dexamethasone (0.25 mg subcutaneously) or vehicle (corn oil). The ability of isoproterenol to induce and maintain inhibition of contractile activity was determined in vitro. In addition, the density and affinity of beta-adrenergic receptors was estimated by ligand binding and Scatchard analysis.
Dexamethasone significantly increased both the duration of myometrial responsiveness to isoproterenol and the beta-adrenergic receptor number at parturition, but not at other time points. Regardless of pretreatment, the susceptibility of the myometrium to beta-agonist-induced desensitization was greatest around the time of delivery.
In the rat, beta-adrenergic agonists are least effective in maintaining myometrial inhibition peripartum, although their effectiveness at this time only can be increased by dexamethasone.
我们研究的目的是确定子宫肌层对β-肾上腺素能激动剂诱导的脱敏作用的敏感性，并确定地塞米松预防这种同源脱敏的能力。
在注射地塞米松（0.25mg皮下注射）或赋形剂（玉米油）12小时后，从未怀孕、怀孕和产后大鼠（n≥6）收集子宫肌层组织。在体外确定异丙肾上腺素诱导和维持收缩活性抑制的能力。此外，通过配体结合和Scatchard分析估计β-肾上腺素能受体的密度和亲和力。
地塞米松显著增加了分娩时子宫肌层对异丙肾上腺素反应的持续时间和β-肾上腺素能受体数量，但在其他时间点没有增加。无论预处理如何，子宫肌层对β-激动剂诱导的脱敏作用的敏感性在分娩时最高。
在大鼠中，β-肾上腺素能激动剂在维持围产期子宫肌层抑制方面效果最差，尽管此时它们的有效性仅可通过地塞米松提高。
