Surgery (Otolaryngology), Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06510, USA.
Neuroscience, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06510, USA.
Sci Rep. 2020 Apr 10;10(1):6222. doi: 10.1038/s41598-020-63201-6.
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）代表了 prestin（SLC26a5）的电压传感器电荷运动，该蛋白负责 OHC 的电运动。先前对 NLC 频率响应的测量采用了未评估介电损耗（传感器电荷与电压不同相）影响的方法，而这种损耗可能会影响 prestin 的频率依赖性活性。在这里，我们评估了 prestin 的复电容高达 30kHz，并发现使用这种方法确定的 prestin 频率响应与所有先前的估计一致。我们还表明，尽管 prestin 的电压工作范围发生了很大变化，但膜张力对其频率响应没有影响，这表明 prestin 转换速率的变化不能解释这些变化。在频率上，prestin 活性的幅度下降超过了已知消除耳蜗放大作用的水杨酸盐处理引起的 NLC 减少。这种下降可能限制了 prestin 在一些哺乳动物处理的非常高的声频率下对耳蜗放大的有效性。
