外源性硫化氢及K_(ATP)通道对大鼠慢性应激结肠高动力的调节

目的:研究外源性硫化氢(hydrogen sulfide,H2S)及ATP敏感性钾通道(ATP-sensitive potassium channels,KATP)在慢性应激结肠高动力中的作用。方法:制作慢性避水应激(water avoidance stress,WAS)和假避水应激(sham water avoidance stress,SWAS)大鼠模型,观察2组大鼠结肠肌条的收缩活性以及硫氢化钠(Na HS)和格列本脲预处理后对2组大鼠结肠肌条收缩影响并计算Na HS的半数抑制浓度(half maximal inhibitory concentration,IC50),使用免疫荧光及Western blotting法观察KATP通道各亚基在结肠中的分布及表达。结果:WAS组结肠肌条收缩活性明显高于SWAS组;Na HS浓度依赖性抑制2组大鼠纵行肌(longitudinal muscle,LM)和环形肌(circular muscle,CM)的收缩;WAS组LM和CM的Na HS IC50分别为0.2033 mmol/L和0.1438 mmol/L,均明显低于SWAS组(P0.01);格列本脲明显增加2组大鼠肌条Na HS IC50(P0.01);Kir6.1、Kir6.2和SUR-2B在2组大鼠结肠固有肌细胞膜均有分布;WAS组(去除黏膜及黏膜下层后)Kir6.1和SUR2B蛋白表达高于SWAS组(P0.01)。结论:H2S外源性供体Na HS对慢性应激结肠高动力具有潜在的治疗作用。KATP通道亚基Kir6.1/SUR2B表达增加可能是慢性应激结肠动力紊乱的一种适应性反应。

Effect of exogenous H2S and ATP-sensitive potassium channels on colonic hypermotility in a rat model of chronic stress

AIM: To investigate the potential role of exogenous hydrogen sulfide (H₂S) and ATP-sensitive potassium (K_ATP) channels in chronic stress-induced colonic hypermotility.METHODS: Male Wistar rats were divided into water avoidance stress (WAS) group and sham WAS (SWAS) group. Organ bath recordings were used to test the contractile activity of colonic strips. The effects of H₂S donor NaHS and pretreatment with glibenclamide on the contractions of colonic smooth muscle were studied and the IC₅₀ of NaHS was calculated. The localization and expression of the subunits of K_ATP channels were determined by the methods of immunohistochemistry and Western blotting.RESULTS: WAS increased contractile activity of colonic strips. NaHS concentration-dependently inhibited the spontaneous contractions of strips from the SWAS and WAS rats. The IC₅₀ of NaHS for longitudinal muscle (LM) and circular muscle (CM) of the WAS rats was 0.2033 mmol/L and 0.1438 mmol/L, significantly lower than those of the SWAS rats. Glibenclamide significantly increased the IC₅₀ of NaHS for LM and CM from the SWAS and WAS rats. In both SWAS and WAS rat colon, Kir6.1, Kir6.2 and SUR2B were expressed on the plasma membrane of the smooth muscle cells. WAS treatment resulted in up-regulation of the expression of Kir6.1 and SUR2B in the colon devoid of mucosa and submucosa.CONCLUSION: The increased expression of Kir 6.1 and SUR2B in colonic smooth muscle cells may be a defensive response to chronic WAS. H₂S donors may have potential clinical effect on treating chronic stress-induced colonic hypermotility.