Duong Dinh Thien An, Haasler Thorsten, Homann Georg, Jüngling Eberhard, Westhofen Martin, Lückhoff Andreas
Institute of Physiology, Medical Faculty, RWTH Aachen, 52057 Aachen, Germany.
Pflugers Arch. 2009 Jun;458(2):379-87. doi: 10.1007/s00424-008-0622-2. Epub 2008 Dec 16.
Vestibular type II hair cells respond to increases in the hydrostatic pressure with pressure-dependent K(+) currents. We examined whether such currents may modulate transmitter release (assessed as membrane capacitance increments) by altering membrane potentials and voltage-gated Ca(2+) currents. Capacitance increments were dependent on voltage-gated Ca(2+) influx. Stimulating currents (0.7 nA) in current clamp induced depolarisations that were more negative by 8.7 +/- 2.1 mV when the bath height was elevated from 0.2 to 0.5 cm. In voltage clamp, protocols were used that simulated the time course of the membrane potential in current clamp at either low (control) or high hydrostatic pressure (high bath). The low bath protocol induced significantly larger Ca(2+) currents and increases in capacitance than the high bath protocol. We conclude that pressure-dependent K(+) currents may alter the voltage response of vestibular hair cells to an extent critical for Ca(2+) currents and transmitter release. This mechanism may contribute to vestibular dysfunction in Meniere's disease.
前庭II型毛细胞通过压力依赖性钾电流对静水压力的增加做出反应。我们研究了此类电流是否可能通过改变膜电位和电压门控钙电流来调节递质释放（以膜电容增加来评估）。电容增加依赖于电压门控钙内流。在电流钳模式下，刺激电流（0.7 nA）诱导的去极化在浴槽高度从0.2 cm升高到0.5 cm时，负电位增加了8.7±2.1 mV。在电压钳模式下，采用了模拟电流钳模式下低（对照）或高静水压力（高浴槽）时膜电位时间进程的方案。低浴槽方案诱导的钙电流和电容增加比高浴槽方案显著更大。我们得出结论，压力依赖性钾电流可能在对钙电流和递质释放至关重要的程度上改变前庭毛细胞的电压反应。这种机制可能导致梅尼埃病中的前庭功能障碍。
