ACTION OF SALICYLATE ON MEMBRANE CAPACITANCE OF OUTER HAIR-CELLS FROM THE GUINEA-PIG COCHLEA
ACTION OF SALICYLATE ON MEMBRANE CAPACITANCE OF OUTER HAIR-CELLS FROM THE GUINEA-PIG COCHLEA
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DOI：
10.1113/jphysiol.1995.sp020765
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发表时间：
1995-06-15
影响因子：
5.5
通讯作者：
ASHMORE, JF
中科院分区：
文献类型：
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作者：
TUNSTALL, MJ;GALE, JE;ASHMORE, JF
1.水杨酸对膜电容和细胞内pH值的影响已被测量在分离的外毛细胞（OHC）在全细胞记录。采用锁相放大技术测量细胞膜电容.在浴中施加水杨酸盐减少了快速电荷移动，相当于存在于OHC中的电压依赖性膜电容。同时测量膜电容和电压驱动的细胞长度变化表明水杨酸盐同时降低了两者.在0 mV时，水杨酸盐对外向电流的影响很小。水杨酸钠（5 mM）使OHC的外向电流减少19%，另一种弱酸丁酸钠（10 mM）使OHC的外向电流减少15%。比率染料2，7-双（2-羧甲基）-5，6-羧基荧光素（BCECF）用于测量弱酸暴露期间OHC中pH（i）的变化。在首先暴露于10 mM丁酸钠然后暴露于5 mM水杨酸钠的OHC中同时测量膜电容和pH（i）。虽然两种化合物产生类似的pH（i）降低，但丁酸盐使静息电容从35 pF（在-30 mV下）的平均静息电容降低5.4 +/-2.1 pF，而水杨酸盐使其降低15.7 +/-2.3 pF（n = 4）。OHC暴露于10 mM苯甲酸钠（一种两亲性阴离子），在-30 mV下使静息膜电容降低9.2 +/- 3.2 pF（n = 3）。在苯甲酸盐应用期间，在0 mV下测量的外向电流降低了0.25 +/- 0.05 nA，与水杨酸盐的作用相当。在水杨酸盐的缓慢浴施加期间测量电容。由此产生的剂量-电容曲线的希尔系数为3.40 +/- 0.85（n = 4），半最大剂量为3.95 +/- 0.34 mM。剂量-电容曲线没有明显的电压依赖性。水杨酸盐对Deiters细胞的静息电容没有可检测的影响，Deiters细胞是Corti器官的非感觉细胞类型。它的结论是，许多水杨酸对听力的影响可能会产生从分区的水杨酸分子到OHC的膜和随之而来的抑制OHC运动。
1. The effect of salicylate on membrane capacitance and intracellular pH has been measured in isolated outer hair cells (OHCs) during whole cell recording. Cell membrane capacitance was measured using a lock-in amplifier technique.2. Salicylate applied in the bath reduced the fast charge movement, equivalent to a voltage-dependent membrane capacitance, present in OHCs. Simultaneous measurement of membrane capacitance and voltage-driven cell length changes showed that salicylate reduced both together.3. A small effect of salicylate on outward currents at 0 mV was observed. Sodium salicylate (5 mM) reduced the currents by 19% and another weak acid, sodium butyrate (10 mM), reduced outward currents in OHCs by 15%.4. The ratiometric dye 2,7-bis(2-carboxymethyl)-5,6-carboxyfluorescein (BCECF) was used to measure pH(i) changes in OHCs during weak acid exposure. Membrane capacitance and pH(i) were measured simultaneously in OHCs exposed first to 10 mM sodium butyrate and then to 5 mM sodium salicylate. Although both compounds produced a similar reduction in pH(i), butyrate decreased the resting capacitance from a mean resting capacitance of 35 pF (at -30 mV) by 5.4 +/- 2.1 pF, whereas salicylate decreased it by 15.7 +/- 2.3 pF (n = 4).5. Exposure of OHCs to 10 mM sodium benzoate, an amphiphilic anion, reduced resting membrane capacitance at -30 mV by 9.2 +/- 3.2 pF (n = 3). Outward currents, measured at 0 mV, were reduced by 0.25 +/- 0.05 nA during benzoate application, comparable with the effect of salicylate.6. Capacitance was measured during slow bath application of salicylate. The resulting dose-capacitance curve had a Hill coefficient of 3.40 +/- 0.85 (n = 4) and a half-maximal dose of 3.95 +/- 0.34 mM. The dose-capacitance curve was not significantly voltage dependent.7. Salicylate had no detectable effect on the resting capacitance of Deiters' cells, a non-sensory cell type of the organ of Corti.8. It is concluded that many of the described effects of salicylate on hearing may arise from the partitioning of the salicylate molecule into the membrane of the OHC and consequent inhibition of OHC motility.