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目的 观察外毛细胞内源性钙离子的释放。方法 分离豚鼠耳蜗外毛细胞 ,用硫汞撒(thimerosal)为激动剂 ,用钙离子敏感染料Fura 2和数字荧光显微镜观察离体外毛细胞内钙离子浓度的波动。结果 硫汞撒可诱发离体耳蜗外毛细胞胞内钙离子的明显增加 ,其增加程度在一定范围内与硫汞撒的浓度呈正比。在清除了细胞外液中钙离子后 ,硫汞撒仍可诱发离体耳蜗外毛细胞胞内钙离子浓度的升高。在此钙离子浓度升高的基础上向胞外液加入钙离子 ,胞内钙浓度进一步升高 ;它可被 5 0 0 μmol/L非选择性钙通道阻断剂LaCl3 阻断。而L型电压激活的钙通道阻滞剂硝苯吡啶对其无阻断作用。硫汞撒的作用可被巯基保护剂二硫苏糖醇阻断和逆转。百日咳毒素、咖啡因和理阿诺碱对硫汞撒的作用无影响。结论 巯基氧化剂硫汞撒可通过两条途径使外毛细胞胞内钙离子浓度升高 ,一是诱发离体外毛细胞内咖啡因和理阿诺碱咖啡因和理阿诺碱不敏感的内源性钙离子释放 ,二是通过硝苯吡啶不敏感的非特异钙通道使钙离子从胞外内流。对巯基氧化启动的钙通道值得进一步研究
Objective To observe the release of endogenous calcium ion in outer hair cells. Methods The cochlear outer hair cells of guinea pigs were isolated and the fluctuations of intracellular calcium concentration in vitro were observed by Fura 2 and digital fluorescence microscope with thimerosal as agonist. Results Thimerosal induced a significant increase of intracellular calcium in cochlear outer hair cells, and the degree of increase was proportional to the concentration of thimerosal in a certain range. Thiomersal still induced an increase in the intracellular calcium concentration in isolated outer hair cells of cochlear cells after calcium ions were removed from the extracellular fluid. Calcium was added to the extracellular fluid on the basis of this increase in calcium ion concentration, and the intracellular calcium concentration was further increased; it was blocked by LaCl3, a non-selective calcium channel blocker of 500 μmol / L. The L-type voltage-activated calcium channel blocker nifedipine non-blocking effect. The effect of thimerosal can be blocked and reversed by the thiol protective agent dithiothreitol. Pertussis toxin, caffeine and lignin base had no effect on thimerosal. Conclusions Mercaptathione (Thiomicrosin) can increase the concentration of intracellular calcium in outer hair cells by two ways. One is inducing the endogenous insensitivity of caffeine and ryanodine caffeine and ryanodine in vitro The second is the release of calcium ions from the extracellular efflux through the non-specific calcium channels that are not sensitive to nifedipine. Thioxy-activated calcium channels deserve further study