Fettiplace Robert, Ricci Anthony J
Department of Physiology, University of Wisconsin Medical School, Madison, WI 53706, USA.
Curr Opin Neurobiol. 2003 Aug;13(4):446-51. doi: 10.1016/s0959-4388(03)00094-1.
The narrow stimulus limits of hair cell transduction, equivalent to a total excursion of about 100nm at the tip of the hair bundle, demand tight regulation of the mechanical input to ensure that the mechanoelectrical transducer (MET) channels operate in their linear range. This control is provided by multiple components of Ca(2+)-dependent adaptation. A slow mechanism limits the mechanical stimulus through the action of one or more unconventional myosins. There is also a fast, sub-millisecond, Ca(2+) regulation of the MET channel, which can generate resonance and confer tuning on transduction. Changing the conductance or kinetics of the MET channels can vary their resonant frequency. The tuning information conveyed in transduction may combine with the somatic motility of outer hair cells to produce an active process that supplies amplification and augments frequency selectivity in the mammalian cochlea.
毛细胞转导的刺激范围狭窄，相当于毛束顶端约100纳米的总偏移，这就要求对机械输入进行严格调节，以确保机电转导（MET）通道在其线性范围内运作。这种控制由钙依赖适应性的多个组件提供。一种缓慢的机制通过一种或多种非常规肌球蛋白的作用来限制机械刺激。MET通道还存在快速的、亚毫秒级的钙调节，这种调节可产生共振并赋予转导调谐特性。改变MET通道的电导或动力学特性可改变其共振频率。转导过程中传递的调谐信息可能与外毛细胞的体细胞运动相结合，产生一种主动过程，为哺乳动物耳蜗提供放大作用并增强频率选择性。
