Outer hair cell (OHC) nonlinear capacitance (NLC) represents voltage sensor charge movements of prestin (SLC26a5), the protein responsible for OHC electromotility. Previous measures of NLC frequency response have employed methods which did not assess the influence of dielectric loss (sensor charge movements out of phase with voltage) that may occur, and such loss conceivably may influence prestin’s frequency dependent activity. Here we evaluate prestin’s complex capacitance out to 30 kHz and find that prestin’s frequency response determined using this approach coincides with all previous estimates. We also show that membrane tension has no effect on prestin’s frequency response, despite substantial shifts in its voltage operating range, indicating that prestin transition rate alterations do not account for the shifts. The magnitude roll-off of prestin activity across frequency surpasses the reductions of NLC caused by salicylate treatments that are known to abolish cochlear amplification. Such roll-off likely limits the effectiveness of prestin in contributing to cochlear amplification at the very high acoustic frequencies processed by some mammals.

外毛细胞 (OHC) 非线性电容 (NLC) 代表 prestin (SLC26a5)（负责 OHC 电动性的蛋白质）的电压传感器电荷运动。以前的 NLC 频率响应测量所采用的方法没有评估可能发生的介电损耗（传感器电荷运动与电压异相）的影响，并且可以想象，这种损耗可能会影响 prestin 的频率依赖性活动。在这里，我们评估了 prestin 的复数电容，最高可达 30 kHz，发现使用这种方法确定的 prestin 频率响应与之前的所有估计一致。我们还表明，尽管 prestin 的电压工作范围发生了很大的变化，但膜张力对 prestin 的频率响应没有影响，这表明 prestin 转换率的变化并不能解释这些变化。 prestin 活性随频率的衰减幅度超过了水杨酸盐治疗引起的 NLC 降低，水杨酸盐治疗已知可消除耳蜗放大。这种滚降可能限制了 prestin 在某些哺乳动物处理的极高声频下促进耳蜗放大的有效性。