17β-雌二醇对大鼠子宫平滑肌自发和激发收缩活动的抑制作用

Inhibitory effects of 17β-estradiol on spontaneous and activated contraction of rat uterus smooth muscle

目的:探讨17β-雌二醇(EST)对离体SD大鼠子宫平滑肌收缩活动的影响。方法:将SD大鼠子宫平滑肌放置于灌流肌槽中,累积加入不同浓度EST溶液,记录肌肉收缩活动的变化。结果:EST可浓度依赖性地抑制子宫平滑肌自发性节律收缩,明显降低其收缩张力和节律性收缩频率,减小收缩波振幅(P<0.01);也可抑制KCl、Ca-Cl2及前列腺素F2α(PGF2α)激发的收缩运动。在EST抑制KCl激发收缩运动中,用线性回归法计算:IC50=7.278μmol/L,pD2=-0.862;在EST抑制CaCl2量效曲线收缩活动中,用线性回归法计算:EC50=1.422×10-3mol/L,pD2=2.847(对照组);EC50=3.028×10-3mol/L,pD2=2.519(EST组)。结论:EST可抑制子宫平滑肌自发和激发收缩活动,其作用可能主要通过抑制电压依赖性钙通道介导的胞外Ca2+内流实现。

Objective： To observe and compare the effects of 17β-estradiol（EST） on the phasic and tonic contractile activities of the uterine smooth muscles of SD rats in vitro.Methods： Different concentrations of 17β-estradiol were added into the perfusion muscular sockets containing uterine smooth muscles of SD rats,and the activities of muscle contraction were recorded at the same time.Results： 17β-estradiol had obvious depression effects on spontaneous rhythmic contraction of the uterine smooth muscles in a concentration-dependent manner,it could considerably decrease muscular tension,the mean amplitudes and frequencies of contractile waves（P＆lt;0.01）;it could also suppress the uterine contraction stimulated by KCl,CaCl2 or prostaglandin F2α（PGF2α）.Based on the contraction of uterine smooth muscle stimulated by KCl,IC50 was 7.278 μmol/L and pD2 was-0.862 when calculated by linear regression method.17β-estradiol could also inhibit the maximal CaCl2 contraction of uterine smooth muscle in the Ca2＋ free Krebs solution,which the EC50 was 1.422×10-3 mol/L,pD2 was 2.847（control）,but the EC50 was 3.028×10-3 mol/L,pD2 was 2.519（added with EST） when calculated by linear regression method.Conclusion： The depression effects of 17β-estradiol on the spontaneous rhythmic contraction and activated contraction of the uterine smooth muscles of SD rats could be mediated through the blockage of Ca2＋ influx through potential-dependent Ca2＋ channels of plasma membrane.