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arXiv 1601.01643physics.bio-ph
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单个外毛细胞的能量输出

Energy output from a single outer hair cell

Kuni H Iwasa

摘要:

外毛细胞(outer hair cells,OHC)的电活动性在耳蜗放大器中具有重要的生理意义,因而在体外实验中得到了广泛的研究。然而,这些研究主要是在无负荷条件下或在静态负荷下进行的,而这些细胞在动态环境中在体内起作用,接收电能以增强内耳中的机械振荡。这种差距在解决一个关键问题时留下了不确定性,即OHC提供多少机械能。本报告是一个尝试,通过引入一个简单的一维模型在动态环境中的OHC的电活动性的差距。该模型采用了一个反馈回路,涉及受体电位和OHC上的机械负载,并导致膜电容的解析表达式,它明确地描述了依赖于弹性负载,粘性阻力,和质量。推导出的运动方程在一个无质量的模型系统中进行了检查,具有现实的参数值OHC。有人发现,粘性阻力是更有效的比弹性负载在提高受体电位驱动的细胞。因此,可以预期OHC在抵消粘性阻力方面比向系统提供弹性能量更有效。

英文摘要:

Electromotility of outer hair cells (OHCs) has been extensively studied with in vitro experiments because of its physiological significance in the cochlear amplifier, which provides the exquisite sensitivity and frequency selectivity of the mammalian ear. However, these studies have been performed largely under load-free conditions or with static load, while these cells function in vivo in a dynamic environment, receiving electrical energy to enhance mechanical oscillation in the inner ear. This gap leaves uncertainties in addressing a key issue, how much mechanical energy an OHC provides. The present report is an attempt of bridging the gap by introducing a simple one-dimensional model for electromotility of OHC in a dynamic environment. This model incorporates a feedback loop involving the receptor potential and the mechanical load on OHC, and leads to an analytical expression for the membrane capacitance, which explicitly describes the dependence on the elastic load, viscous drag, and the mass. The derived equation of motion was examined in a mass-less model system with realistic parameter values for OHC. It was found that viscous drag is more effective than elastic load in enhancing the receptor potential that drives the cell. For this reason, it is expected that OHCs are more effective in counteracting viscous drag than providing elastic energy to the system.

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