【摘要】 目的:研究L-型钙离子通道阻断剂硝苯地平（nifedipine）、硫酸镁对人妊娠子宫平滑肌收缩功能的抑制作用及其与临产的关系。方法:剖宫产时取足月妊娠临产、未临产子宫下段平滑肌,将肌条置于组织器官浴中,加入催产素(10^-9mol/L)诱发平滑肌收缩,依次加入10^-8、10^-7、10^-6、10^-5mol/L的硝苯地平或1、2、4、8、16 mmol/L的硫酸镁,通过离体肌肉等长张力测定试验,计算用药前后单位时间内子宫收缩的频率、收缩幅度及子宫收缩曲线下面积,并计算药物抑制百分比。结果:硝苯地平对催产素诱发的人妊娠子宫平滑肌收缩的抑制作用呈剂量依赖性,对临产组的抑制作用较未临产组明显减弱,两组比较差异显著（P<0.05）;硫酸镁对人妊娠子宫肌收缩也有抑制作用,但临产组与未临产组比较差异不显著（P>0.05）。结论:硝苯地平对临产后子宫平滑肌的抑制作用下降,可能提示临产后子宫平滑肌对硝苯地平的敏感性发生了改变;硫酸镁对人妊娠子宫肌的抑制作用与是否临产无关,提示Mg²⁺对子宫平滑肌收缩的抑制作用除通过钙离子通道外,可能还有其他作用机制。更多还原

【Abstract】 Objective:To investigate the inhibitory effects of L-type Ca²⁺-channel blocker nifedipine and magnesium sulfate on uterine contractility of full term pregnant women and its relation with labour.Methods:Myometrial strips,prepared from bi- opsies taken at caesarean section from labouring and non-labouring women at full term pregnancy,were mounted in organ cham- bers for isometric tension recording.Oxytocin(10^-9mol/L)was employed to induce stable contraction.The cumulative effects of nifedipine(10^-8,10^-7,10^-6and 10^-5mol/L)and magnesium sulfate（1,2,4,8 and 16 mmol/L）were studied by calculating the frequency,amplitude and AUC of contractions before and after drug applications,and the inhibitory rates were also calculated. Results:Nifedipine exerted a concentration-dependent relaxant effect on human term pregnant myometrial contractions induced by oxytocin.The relaxant effect was greater in the myometrium of non-labouring than that in the labouring group（P<0.05）. Magnesium sulfate also inhibited the contractility in both groups,with no significant difference between the 2 groups（P>0.05）. Conclusion:Decreased inhibition of human uterine contractility by L-type Ca²⁺-channel blocker nifedipine in term labouring myometrium may reflect sensitivity changes of Ca²⁺-channel to nifedipine after the onset of labour.The inhibitory effects of Mg²⁺are not affected by labour,suggesting that Mg²⁺may also exert its effect on contractility through other pathways besides Ca²⁺-channel.更多还原