Russell I J, Cody A R, Richardson G P
Hear Res. 1986;22:199-216. doi: 10.1016/0378-5955(86)90096-1.
Until recently the responses of the mechanosensitive hair cells of the cochlea have been inferred from their morphology, morphological relationships with other structures in the cochlea, and by indirect electrophysiological measurements. With the advent of techniques for making intracellular recordings from hair cells in the cochleas of anaesthetised mammals it has been possible to measure the responses of hair cells to acoustic stimulation and to assess their roles in sensory transduction in the cochlea. Intracellular recordings of the responses of inner and outer hair cells in the basal turn of the guinea-pig cochlea show that they differ considerably from each other. The receptor potentials of inner hair cells are larger, predominantly depolarizing to low frequency tones and at their best frequencies (16-20 kHz) they generate depolarizing dc receptor potentials. Outer hair cells generate predominantly hyperpolarizing potentials to low frequency tones. They do not produce significant voltage responses at high frequencies except at high intensities when they generate slowly rising depolarizing potentials which are associated with loss of cochlear sensitivity. At low frequencies the receptor potentials of the inner hair cells phase lead those of the outer hair cell. Measurements of their frequency selectivity show that inner and outer hair cells are both sharply tuned. It is proposed that the responses of inner and outer hair cells are consistent with sensory and motor roles respectively in mechanoelectric transduction and that the outer hair cells are the site of an active mechanical process responsible for the frequency selectivity and sensitivity of the cochlea. Intracellular recordings from hair cells in the mouse cochlea maintained in vivo have provided a direct measure of the mechanosensitivity of cochlear hair cells (approximately 30 mV per degree of displacement of their stereociliary bundles) and indirect evidence that the transfer characteristics of the outer hair cells in vivo may be due to their mechanoelectrical interaction with the tectorial membrane. This is because the transfer characteristics of the inner and outer hair cells are similar in vitro in the absence of a tectorial membrane. Considerable importance is attributed to the shape of the transfer characteristics of the inner and outer hair cells. Changes in these characteristics during anoxia and following exposure to intense tones are associated with depolarization of the outer hair cells and loss of cochlear sensitivity and frequency selectivity. Current-voltage studies of hair cells in vivo show the inner and outer hair cells to be electrically nonlinear.(ABSTRACT TRUNCATED AT 400 WORDS)
直到最近，人们一直通过耳蜗机械敏感毛细胞的形态、它们与耳蜗中其他结构的形态关系以及间接电生理测量来推断其反应。随着从麻醉哺乳动物耳蜗中的毛细胞进行细胞内记录技术的出现，现在已经能够测量毛细胞对声刺激的反应，并评估它们在耳蜗感觉转导中的作用。对豚鼠耳蜗基底转内、外毛细胞反应的细胞内记录表明，它们彼此有很大差异。内毛细胞的感受器电位较大，主要对低频音调去极化，在其最佳频率（16 - 20千赫）时，它们产生去极化直流感受器电位。外毛细胞对低频音调主要产生超极化电位。除了在高强度时产生缓慢上升的去极化电位（这与耳蜗敏感性丧失有关）外，它们在高频时不会产生明显的电压反应。在低频时，内毛细胞的感受器电位相位领先于外毛细胞。对它们频率选择性的测量表明，内、外毛细胞都具有尖锐的调谐。有人提出，内、外毛细胞的反应分别与机械电转导中的感觉和运动作用一致，并且外毛细胞是负责耳蜗频率选择性和敏感性的主动机械过程的部位。在体内维持的小鼠耳蜗毛细胞的细胞内记录直接测量了耳蜗毛细胞的机械敏感性（其静纤毛束每位移一度约为30毫伏），并间接证明体内外毛细胞的传递特性可能是由于它们与盖膜的机电相互作用。这是因为在没有盖膜的情况下，内、外毛细胞在体外的传递特性相似。内、外毛细胞传递特性的形状被认为具有相当重要的意义。在缺氧期间以及暴露于高强度音调后，这些特性的变化与外毛细胞的去极化以及耳蜗敏感性和频率选择性的丧失有关。对体内毛细胞的电流 - 电压研究表明，内、外毛细胞在电方面是非线性的。（摘要截于400字）
