Weiss T F, Leong R
Hear Res. 1985;20(2):175-95. doi: 10.1016/0378-5955(85)90167-4.
A model is described for mechanoelectric transduction in hair cells with free-standing stereocilia in the alligator lizard cochlea. The model relates the angular displacement of the stereocilia to the receptor potential in the absence of the hair cell's membrane capacitance whose effect is considered elsewhere (Leong and Weiss, 1985, in preparation). The model consists of two parts: a population of membrane ionic channels and an electric network that relates the channel conductance to the equivalent resistance of the hair cell. The membrane ionic channels tend to open when the stereociliary tuft is displaced toward the kinocilium (or basal body) and tend to close when the tuft is oppositely displaced. The fraction of channels that is open for a given tuft displacement is governed by Boltzmann statistics and the energies of open and closed configurations of the channels are separated by a single energy barrier whose height depends on the angular displacement of the stereociliary tuft. The resulting channel conductance is a hyperbolic-tangent type function of the angular displacement of the stereociliary tuft. The channel conductance is coupled to the rest of the hair cell by an equivalent electric network containing constant resistance and a capacitance. The Thévenin equivalent resistance change across the basolateral membrane of the hair cell, called the transducer function, is also a hyperbolic-tangent type function of angular displacement. The parameters of the channel conductance and the values of resistances in the hair-cell electric model determine the scale factors and the location of the operating point of this hyperbolic-tangent type function. The hyperbolic-tangent type function is a specific example of a class of monotonically decreasing and saturating, or sigmoidal, transducer functions. The spectral properties of sigmoidal transducer functions are examined for sinusoidal angular displacements of amplitude theta. General results are obtained for arbitrary sigmoidal transducer functions; particular results are obtained for the hyperbolic-tangent type function. General conclusions concerning spectral components of the resistance change include: all spectral components are independent of the frequency of the angular displacement; the constant or DC component can be positive or negative; the fundamental component is 180 degrees out of phase with the angular displacement, i.e. the resistance decreases when the stereocilia are displaced towards the kinocilium; for small values of theta, the magnitude of the nth harmonic tends to grow as theta n for n greater than 0; the zeroth harmonic or DC component grows as theta 2.(ABSTRACT TRUNCATED AT 400 WORDS)
本文描述了一种关于钝吻鳄耳蜗中具有独立静纤毛的毛细胞机电转换的模型。该模型在不考虑毛细胞膜电容（其影响在其他地方讨论，见Leong和Weiss，1985，正在准备中）的情况下，将静纤毛的角位移与感受器电位联系起来。该模型由两部分组成：一群膜离子通道和一个将通道电导与毛细胞等效电阻联系起来的电网络。当静纤毛束朝着动纤毛（或基体）位移时，膜离子通道倾向于打开；当毛束反向位移时，通道倾向于关闭。对于给定的毛束位移，打开的通道比例由玻尔兹曼统计规律决定，通道打开和关闭构型的能量由一个单一的能垒分隔，其高度取决于静纤毛束的角位移。由此产生的通道电导是静纤毛束角位移的双曲正切型函数。通道电导通过一个包含恒定电阻和电容的等效电网络与毛细胞的其余部分耦合。毛细胞基底外侧膜上的戴维南等效电阻变化，即换能函数，也是角位移的双曲正切型函数。通道电导的参数和毛细胞电模型中的电阻值决定了该双曲正切型函数的比例因子和工作点位置。双曲正切型函数是一类单调递减且饱和的，或S形的换能函数的一个具体例子。对于振幅为θ的正弦角位移，研究了S形换能函数的频谱特性。得到了任意S形换能函数的一般结果；对于双曲正切型函数得到了具体结果。关于电阻变化频谱成分的一般结论包括：所有频谱成分都与角位移的频率无关；常数或直流成分可以是正的或负的；基波成分与角位移相位相差180度，即当静纤毛朝着动纤毛位移时电阻减小；对于小的θ值，当n大于0时，第n次谐波的幅度倾向于随着θ^n增长；零次谐波或直流成分随着θ^2增长。（摘要截于400字）
