IONIC BASIS OF MEMBRANE-POTENTIAL IN OUTER HAIR-CELLS OF GUINEA-PIG COCHLEA
IONIC BASIS OF MEMBRANE-POTENTIAL IN OUTER HAIR-CELLS OF GUINEA-PIG COCHLEA
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DOI：
10.1038/322368a0
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发表时间：
1986-07-24
期刊：
影响因子：
64.8
通讯作者：
MEECH, RW
中科院分区：
文献类型：
--
作者：
ASHMORE, JF;MEECH, RW
哺乳动物的听觉包括其他物种所没有的特征，例如，声音频率的分离依赖于对耳蜗机制的主动控制1,2。耳蜗中产生力的成分可能是外毛细胞（OHC），它是位于耳蜗顶端表面的机电传感器通道对电流进行门控的两种感觉细胞之一。体外分离的外毛细胞已被证明是可运动的，并且能够在声波频率下产生力。然而，OHC膜不像在低等脊椎动物中发现的那样是电调谐的。在这里，我们描述了OHC静息电位是如何由Ca2+激活的K+电导决定的10,11在细胞的底部。钙离子激活的K+电导由两种通道类型构成，其大小分别为240和45 pS，我们认为它们的活性是由钙离子通过顶端换能器通道内流决定的，这在其他毛细胞中也得到了证实12。这种耦合系统同时解释了在活体中观察到的大OHC静息电位13,14，并表明了由换能器门控的电流如何最大化以产生耳蜗微力学所需的力。
Mammalian hearing involves features not found in other species, for example,the separation of sound frequencies depends on an active control of the cochlear mechanics1,2.The force-generating component in the cochlea is likely to be the outer hair cell(OHC), one of the two types of sensory cell through which current is gated by mechano-electrical transducer channels sited on the apical surface3.Outer hair cells isolatedin vitrohave been shown to be motile4,5and capable of generating forces at acoustic frequencies6. The OHC membrane is not, however, electrically tuned, as found in lower vertebrates7–9. Here we describe how the OHC resting potential is determined by a Ca2+-activated K+conductance10,11at the base of the cell. Two channel types with unitary sizes of 240 and 45 pS underlie this Ca2+-activated K+conductance and we suggest that their activity is determined by a Ca2+influx through the apical transducer channel, as demonstrated in other hair cells12. This coupled system simultaneously explains the large OHC resting potentials observedin vivo13,14and indicates how the current gated by the transducer may be maximized to generate the forces required in cochlear micromechanics.