SK3表达在雌二醇介导的大鼠结肠平滑肌收缩中的作用

The effect of small-conductance Ca^(2+)-activated K^+ channel 3 expression on relaxation of rat colonic smooth muscle regulated by estrogen

目的:探讨小电导钙激活钾通道3(SK3)表达在17β-雌二醇(E2)介导的大鼠结肠平滑肌收缩中的作用及机制。方法:将24只雄性SD大鼠随机分为4组。30 mm硅胶管皮下植入大鼠背部,内含不同溶液。分为对照组(C),内含溶剂;生理剂量组(EP)内含E2 0.3 mg/m L,使大鼠血清雌激素在生理浓度;超剂量组(ES)内含E2 0.9 mg/m L,使大鼠血清雌激素超生理浓度;ER抑制剂+E2组(EI)内含相同摩尔浓度E2和雌激素受体抑制剂(ICI 182780)。各组干预14 d后处理,免疫荧光及Western blot检测结肠平滑肌组织SK3分布及表达;MPA分析系统记录肌条收缩张力及对卡巴胆碱(Cch)刺激反应。E2孵育结肠平滑肌细胞(SMC)24 h后及过表达SK3后,激光共聚焦显微镜下动态观察Cch刺激后SMC内Ca^(2+)变化。结果:Cch刺激后,EP组及ES组肌条收缩明显低于其他各组(P<0.05)。EP组及ES组平滑肌组织SK3表达高于C组及EI组,其中ES组有统计学意义(P<0.05)。Cch刺激后,E2孵育组及过表达SK3组胞内Ca^(2+)上升幅度较相应对照组显著降低(P<0.05)。结论:E2可能通过促进SK3表达,减少Ca^(2+)内流从而抑制结肠收缩。

Objective：The aim of the study was to explore the effect and possible mechanism of 17 β-estradiol（E2）on the expression of small conductance Ca^2＋activated K＋channel 3（SK3）in rat colonic smooth muscle. Method：24 male Sprague-Dawley（SD）rats were randomly divided into 4 groups. Silicone tubes containing different solution was subcutaneously implanted in different groups of rats. Group C was filled with the solvent;Group EP was E2 in corn oil（0.3 mg/m L）which can keep serum levels of E2 at physiological levels;Group ES was E2 in corn oil（0.9 mg/m L）which can keep serum levels of E2 at supraphysiologic levels;Group EI was ICI 182780（estrogen receptor antagonist）plus E2（0.3 mg/m L）. The contraction of muscle strips and SK3 expression in colonic smooth muscles were detected at 14 days after tube implanted. SK3 were overexpressed in SMCs and Ca^2＋concentration in cells were detected by laser scanning confocal microscope. Results：The contraction of muscle strips of EP group and ES group is weaker than other groups（P〈0.05）after Cch stimulating. And the SK3 expression was upregulated in EP and ES groups（P〈0.05）. Ca^2＋decreased in SMCs after Cch stimulating in SK3 overexpression group and E2 stimulating group compared with control group. Conclusion：These findings indicate that E2 may suppress contraction of colonic smooth muscle by upregulating expression of SK3 and inhibiting Ca^2＋influx in rats.