【摘要】 目的探讨硝苯地平对高浓度三磷酸腺苷(ATP)引起的豚鼠耳蜗单离 Hensen 细胞非选择性内向性离子流的影响。方法采用酶消化和机械分离的方法单离豚鼠耳蜗 Hensen 细胞,选择胞膜清晰、胞质透明的单离细胞通过压力注射仪分别给予 0.1 mmol/L ATP、1 mmol/L ATP、10 mmol/LATP、0.1 mmol/L ATP+0.1 mmol/L 舒拉明、单独细胞外液、140 mmol/L CsC1+1mmol/L ATP、40 mmoL/L 四乙基铵(tetraethylammonium,TEA)+1mmol/L ATP、1mmol/L ATP+10 wmol/L 硝苯地平,并行全细胞膜片钳记录。结果当分别给予 Hensen 细胞0.1 mmol/L(n=10),1mmol/L(n=10),10mmol/L(n=6)的 ATP 刺激时,均可记录到内向电流,并随 ATP 浓度的增加而增强,呈现浓度依赖性。该内向电流可被0.1 mmol/L 舒拉明(n=5),140 mmol/L CsC1(n=5)和40 mmol/L TEA(n=5)所抑制。单独给予细胞外液刺激后未见内向及外向离子流。当同时给予 1mmol/L ATP 和 10 μmol/L硝苯地平刺激时,内向性电流消失,转而出现外向性电流。结论高浓度 ATP 可引起 Hensen 细胞的内向性电流,此电流与钾通道密切相关,并无机械转化通道参与,硝苯地平可抑制这种内向性电流并出现与正常情况相似的外向性电流。提示硝苯地平可通过 Hensen 细胞改善钾离子循环,起到部分保护耳蜗功能的作用。更多还原

【Abstract】 Objective To investigate the effect of nifedipine on the non-selective inward current of cochlear Hensen cell induced by ATP in high concentrations.Methods The organ of Corti was treated using enzyme,and then dissociated mechanically to isolate Hensen cells.The whole cell patch-clamp technique was used to record ion currents in Hensen cells which had integrated border,round shape and translucent intracellular cytoplasm.Drugs were delivered to the cell by a micro-manigold consisting made by three 100 μm diameter microtubules,including 0.1 mmol/L ATP,1 mmol/L ATP,10 mmol/L ATP, 0.1mmol/L ATP+0.1 mmol/L suramin(purinergic antagonist),stimulation of extracellular fluid alone, 140mmol/L CsC1(replace KCL in intracellular fluid)+1mmol/L ATP,40 mmol/L TEA(blocker of potassium channel)+1mmol/L ATP,and 1mmol/L ATP+10μmol/L nifedipine,respectively.Results When isolated Hensen cell was given 0.1mmol/L(n=10),1mmol/L(n=10),10mmol/L(n=6)ATP separately,an inward ion current could be recorded,which enhanced with increased ATP concentration and showed dose-dependence.Further study indicated that the inward ion current could be inhibited by 0.1 mmol/L suramin(n=5),140mmol/L CsCI(n=5)and 40mmol/L TEA(n=5).There was no ion current be recorded when the cell was stimulated with the extracellular fluid alone,neither inward nor outward.However,the inward ion current vanished and an outward ion current appeared instead,when 1 mmol/L ATP and 10 μmol/L nifedipine were given together(n=5).Conclusions An inward current was evoked in isolated Hensen cell by ATP in high concentrations.This inward current seems to be associated closely with potassium channels without the participation of mechanical channels.Nifedipine can inhibit this inward current and induce an outward current,which is similar to the normal potassium current in isolated ??Hensen cell.It suggests that nifedipine have partly protective effect on the function of cochlea by inducing modulate of the potassium circle of cochlea in Hensen cell’s tache.更多还原