The resting transducer current drives spontaneous activity in prehearing mammalian cochlear inner hair cells.
The resting transducer current drives spontaneous activity in prehearing mammalian cochlear inner hair cells.
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DOI：
10.1523/jneurosci.0803-12.2012
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发表时间：
2012-08-01
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影响因子：
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通讯作者：
Marcotti W
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文献类型：
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作者：
Johnson SL;Kennedy HJ;Holley MC;Fettiplace R;Marcotti W
在未成熟的哺乳动物耳蜗中自发的Ca 2+依赖性电活动被认为是指示感觉毛细胞和听觉通路分化期间的音调定位图的形成。这种活动发生在出生后第一周的内毛细胞（IHC）中，并且沿着耳蜗沿着的模式不同。在出生后的第二周，也就是大多数啮齿动物听力开始之前，IHC的静息膜电位明显更超极化（约-75 mV），目前尚不清楚自发动作电位是否继续发生。我们发现，当小鼠IHC毛束暴露于未成熟耳蜗中存在的估计体内内淋巴Ca 2+浓度（0.3 mM）时，机械换能器通道的开放概率增加，导致细胞去极化至动作电位阈值（约-55 mV）。我们建议，在体内，自发的Ca 2+动作电位本质上是由IHC产生的听力发作，他们很可能会影响最终的感官独立的完善发展中的耳蜗。
Spontaneous Ca2+-dependent electrical activity in the immature mammalian cochlea is thought to instruct the formation of the tonotopic map during the differentiation of sensory hair cells and the auditory pathway. This activity occurs in inner hair cells (IHCs) during the first postnatal week and the pattern differs along the cochlea. During the second postnatal week, which is before the onset of hearing in most rodents, the resting membrane potential for IHCs is apparently more hyperpolarized (about −75 mV) and it remains unclear whether spontaneous action potentials continue to occur. We found that when mouse IHC hair bundles were exposed to the estimated in vivo endolymphatic Ca2+ concentration (0.3 mM) present in the immature cochlea, the increased open probability of the mechanotransducer channels caused the cells to depolarize to around the action potential threshold (about −55 mV). We propose that, in vivo, spontaneous Ca2+ action potentials are intrinsically generated by IHCs up to the onset of hearing and that they are likely to influence the final sensory-independent refinement of the developing cochlea.