Hurd W W, Betz A L, Dombrowski M P, Fomin V P
Department of Obstetrics and Gynecology, University of Michigan Medical Center, Ann Arbor, USA.
Am J Obstet Gynecol. 1998 May;178(5):1077-81. doi: 10.1016/s0002-9378(98)70551-4.
Our purpose was to evaluate the mechanisms of cocaine's effect on both spontaneous and agonist-induced contractility of pregnant human myometrium.
Myometrium was obtained from 42 women at term who were undergoing cesarean section. Myometrial strips were suspended in contraction baths and isometric contractions were measured. Tissue was exposed to various combinations of cocaine, prazosin, desipramine, benzoylecgonine, and procaine. Spontaneous contractility and the contractile responses to increasing concentrations of methoxamine and oxytocin were measured and compared.
Cocaine increased spontaneous myometrial contractility by more than threefold. Prazosin, an alpha-adrenergic antagonist, blocked this effect only for the first 35 minutes of exposure. The cumulative concentration-response to the alpha-adrenergic agonist methoxamine was increased by cocaine in terms of both sensitivity and maximal response. The maximal response to oxytocin, but not the sensitivity, was increased by cocaine by an effect that could not be blocked by prazosin.
Cocaine augments spontaneous and agonist-induced contractility of pregnant human myometrium by mechanisms that appear to be both alpha-adrenergic and nonadrenergic in nature.
我们的目的是评估可卡因对妊娠人类子宫肌层自发收缩和激动剂诱导收缩的作用机制。
从42名足月行剖宫产的妇女身上获取子宫肌层。将子宫肌条悬挂于收缩浴槽中，测量等长收缩。组织分别暴露于可卡因、哌唑嗪、地昔帕明、苯甲酰爱康宁和普鲁卡因的不同组合中。测量并比较自发收缩性以及对甲氧明和缩宫素浓度增加时的收缩反应。
可卡因使子宫肌层自发收缩性增加了三倍多。α-肾上腺素能拮抗剂哌唑嗪仅在暴露的前35分钟阻断了这种作用。就敏感性和最大反应而言，可卡因增加了对α-肾上腺素能激动剂甲氧明的累积浓度-反应。可卡因增加了对缩宫素的最大反应，但未增加敏感性，且哌唑嗪无法阻断该作用。
可卡因通过似乎兼具α-肾上腺素能和非肾上腺素能性质的机制增强妊娠人类子宫肌层的自发收缩和激动剂诱导的收缩。
