Gitter A H, Rudert M, Zenner H P
Sektion Physiologische Akustik, Klinik für Hals-Nasen-Ohrenheilkunde, Universität Tübingen, Germany.
Pflugers Arch. 1993 Jun;424(1):9-14. doi: 10.1007/BF00375096.
Motion or force generation of outer hair cells may contribute to active modulation of cochlear mechanics. In order to determine the force involved in length changes of outer hair cells, a new in vitro method was used. In the first series of experiments, apical and basolateral extracellular spaces of outer hair cells of the guinea-pig cochlea were separated. Changes of the voltage between the two extracellular spaces induced reversible, proportional changes of the cell length of 4.4 nm/mV if the cell had a length of 80 microns. In the second series of experiments, cell elongations in response to negative pressure applied to the basal end of the cells were measured and corrected for frictional effects. From these data, the compliance of the longitudinal axis of the hair cells was calculated. It was 220 +/- 130 m/N (n = 25) and 240 +/- 170 m/N (n = 24) for cells of the third and fourth cochlear turns, respectively, if the water permeability of the cell membrane was neglected. If the water permeability was taken into account, the compliance was probably around 500 m/N [corrected]. Thus, a mechanism that changes the cell length by 1 microm must generate a static force of at least around 2 nN in an outer hair cell of the organ of Corti [corrected]. Electromotility of outer hair cells, induced by changes of the electrical potential difference across the outer hair cell, is a mechanism that generates this force.
外毛细胞的运动或力的产生可能有助于耳蜗力学的主动调节。为了确定外毛细胞长度变化所涉及的力，采用了一种新的体外方法。在第一系列实验中，分离了豚鼠耳蜗外毛细胞的顶端和基底外侧细胞外间隙。如果细胞长度为80微米，两个细胞外间隙之间电压的变化会引起细胞长度4.4纳米/毫伏的可逆、成比例变化。在第二系列实验中，测量了细胞对施加于细胞基底末端的负压的伸长，并对摩擦效应进行了校正。根据这些数据，计算了毛细胞纵轴的顺应性。如果忽略细胞膜的水渗透性，第三和第四耳蜗转细胞的顺应性分别为220±130米/牛顿（n = 25）和240±170米/牛顿（n = 24）。如果考虑水渗透性，顺应性可能约为500米/牛顿[校正后]。因此，在柯蒂氏器的外毛细胞中，一种使细胞长度改变1微米的机制必须产生至少约2纳牛顿的静力[校正后]。由外毛细胞膜电位差变化诱导的外毛细胞电运动性是产生这种力的一种机制。
