利诺吡啶对豚鼠耳蜗外毛细胞和支持细胞钾电流的影响

目的 观察KCNQ家族钾通道特异性阻滞剂利诺吡啶(linopirdine)对豚鼠耳蜗单离外毛细胞和Deiters细胞(支持细胞)总钾电流的影响，初步探讨KCNQ家族钾通道在耳蜗外毛细胞和Deiters细胞的分布。方法 运用膜片钳技术，在全细胞模式下记录正常细胞外液中8个外毛细胞和5个Deiters细胞的总钾电流，并观察100μmol／L利诺吡啶对外毛细胞和Deiters细胞总钾电流的影响。结果 在正常细胞外液中，单离外毛细胞可记录到四乙基二乙胺敏感的外向性钾电流和静息膜电位附近激活的内向性钾电流(the K^ current activated at negative potential，IKn)两种钾电流，而单离Deiters细胞中只记录到外向整流性钾电流。加入100μmol／L利诺吡啶后，外毛细胞中的四乙基二乙胺敏感的钾电流减小，IKn被完全抑制；而Deiters细胞中的外向整流性钾电流大小无变化。结论 KCNQ家族钾通道存在于豚鼠耳蜗外毛细胞，其介导的钾电流是四乙基二乙胺敏感的钾电流的组成部分，并构成全部的IKn；但KCNQ家族钾通道不存在于豚鼠耳蜗Deiters细胞。

Effect of linopirdine on potassium currents in isolated outer hair cells and Deiters'' cells of the cochlea from guinea pig]

OBJECTIVE: To study the effect of linopirdine, a selective blocker of KCNQ channel family, on the whole-cell potassium currents in isolated outer hair cells (OHCs) and Deiters' cells of the cochlea from guinea pig and to probe the distribution of KCNQ channel family in OHC and Deiters' cells. METHODS: Using the patch clamp whole-cell recording, IK (tetraethylammonium-sensitive outward potassium currents) and IKa (inward potassium currents activated at negative potential) were measured before and after the administration of linopirdine in OHCs. Simultaneously, IK (the outward rectifier potassium current) was recorded in Deiters' cells. RESULTS: IK was partly reduced after the administration of linopirdine in OHCs, moreover, IKa was totally inhibited. However, IK in Deiter's cells was not decreased. CONCLUSION: KCNQ channel family could only involve in constructing the variant potassium channels in outer hair cells, but not in Deiters' cells.