一氧化氮对糖尿病小鼠近端结肠动力有抑制作用

目的:研究一氧化氮(NO)对糖尿病小鼠近端结肠收缩功能的作用.方法:制备C57小鼠糖尿病(DM)模型,用硝酸还原酶法检测近端结肠组织NO水平:用免疫印迹法分析近端结肠组织nNOS和iNOS的含量;用免疫荧光染色观察近端结肠中nNOS的分布:用MD-2000生物信号采集分析系统观察NO前体L-精氨酸(L-Arg)、nNOS的抑制剂7-硝基吲唑(7-NI)、iNOS的抑制剂氨基胍(AG)对糖尿病小鼠近端结肠离体肌条肌张力的影响.结果:nNOS主要分布在近端结肠肌层和黏膜下层,DM组nNOS蛋白和NO水平与正常组比较显著升高,未发现有iNOS蛋白表达.DM组小鼠近端结肠肌张力较正常组降低,但收缩频率无改变.L-Arg可显著抑制正常组和DM组小鼠近端结肠肌的张力,7-NI可显著增强正常组和DM组小鼠近端结肠的肌张力,而加入AG前后结肠张力均无显著变化.所有药物对结肠收缩频率无影响.结论:NO抑制结肠平滑肌收缩能力可能是糖尿病结肠动力功能障碍的重要原因,其作用与nNOS在近端结肠表达增多相关.

Effects of nitric oxide on the motility function of the proximal colon of diabetes mellitus mice

Objective:To investigate the role of nitric oxide(NO) on the motility function of proximal colon of diabetes mellitus mice.Methods:The distribution and expression of nNOS in the proximal colon of diabetes mellitus mice were examined by fluorescence microscopy and Western-blotting,respectively.The effect of NO precursor L-arginine(L-Arg),nNOS inhibitor 7-nitroindazole(7-NI ),iNOS Amino guanidine(AG) on the proximal colon muscle strips muscular contractions were monitored by MD-2000 system.Results:The expression of nNOS in the proximal colon was up-regulated in DM group.L-Arg decreased the proximal colon muscle strips contractile tension,7-NI increased the muscle strips contractile tension while AG had no effect.All drugs had no influence on muscle strips contractive frequency.Conclusion:Increased expression of nNOS is demonstrated in the proximal colon of diabetes mellitus mice,and NO may play an important role in the pathogenesis of diabetic proximal colonic dysfunction.