Hair cell bundles: flexoelectric motors of the inner ear.
Hair cell bundles: flexoelectric motors of the inner ear.
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DOI：
10.1371/journal.pone.0005201
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发表时间：
2009
期刊：
影响因子：
3.7
通讯作者：
Rabbitt RD
中科院分区：
文献类型：
--
作者：
Breneman KD;Brownell WE;Rabbitt RD
内耳毛细胞顶端突出的微绒毛（立体纤毛）是活跃的运动结构，可为内耳的振动提供能量并增强对声音的敏感性。发束运动的生物物理机制尚不清楚。在这项研究中，我们检查了静纤毛主动运动的膜屈电起源，并得出结论，它可能是发束机械功率输出的重要贡献者。我们制定了一个真实的静纤毛生物物理模型，其中包含静纤毛尺寸、已知的脂膜挠电系数、机械顺应性和流体阻力。电力通过位移敏感离子通道进入静纤毛，并且由于静纤毛直径小，通过柔性电转换为有用的机械功率输出。该电机增强了与先前描述的机械敏感装置本身相关的分子电机。该模型揭示了静纤毛是一种高效、快速的柔性电动机，可以捕获内耳细胞外电化学势中的能量以产生机械功率输出。功率分析为静纤毛高度与听觉器官的音调组织之间的相关性提供了解释。此外，结果表明，弯曲电对于非哺乳动物听觉器官在高听觉频率下的精致灵敏度和频率选择性可能至关重要，并且可能有助于哺乳动物的“耳蜗放大器”。
Microvilli (stereocilia) projecting from the apex of hair cells in the inner ear are actively motile structures that feed energy into the vibration of the inner ear and enhance sensitivity to sound. The biophysical mechanism underlying the hair bundle motor is unknown. In this study, we examined a membrane flexoelectric origin for active movements in stereocilia and conclude that it is likely to be an important contributor to mechanical power output by hair bundles. We formulated a realistic biophysical model of stereocilia incorporating stereocilia dimensions, the known flexoelectric coefficient of lipid membranes, mechanical compliance, and fluid drag. Electrical power enters the stereocilia through displacement sensitive ion channels and, due to the small diameter of stereocilia, is converted to useful mechanical power output by flexoelectricity. This motor augments molecular motors associated with the mechanosensitive apparatus itself that have been described previously. The model reveals stereocilia to be highly efficient and fast flexoelectric motors that capture the energy in the extracellular electro-chemical potential of the inner ear to generate mechanical power output. The power analysis provides an explanation for the correlation between stereocilia height and the tonotopic organization of hearing organs. Further, results suggest that flexoelectricity may be essential to the exquisite sensitivity and frequency selectivity of non-mammalian hearing organs at high auditory frequencies, and may contribute to the “cochlear amplifier” in mammals.
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