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A Virtual Hair Cell, II: Evaluation of Mechanoelectric Transduction Parameters

Department of Engineering Science and Mechanics, School of Biomedical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061

Correspondence: Address reprint requests to John R. Cotton, Dept. of Engineering Science and Mechanics, 211 Norris Hall, Blacksburg, VA 24061. Tel.: 1-540-231-7979; E-mail: jcotton{at}vt.edu.

The virtual hair cell we have proposed utilizes a set of parameters related to its mechanoelectric transduction. In this work, we observed the effect of such channel gating parameters as the gating threshold, critical tension, resting tension, and Ca²⁺ concentration. The gating threshold is the difference between the resting and channel opening tension exerted by the tip link assembly on the channel. The critical tension is the tension in the tip link assembly over which the channel cannot close despite Ca²⁺ binding. Our results show that 1), the gating threshold dominated the initial sensitivity of the hair cell; 2), the critical tension minimally affects the peak response, (I), but considerably affects the time course of response, I(t), and the force-displacement, F-X, relationship; and 3), higher intracellular [Ca²⁺] resulted in a smaller fast adaptation time constant. Based on the simulation results we suggest a role of the resting tension: to help overcome the viscous drag of the hair bundle during the oscillatory movement of the bundle. Also we observed the three-dimensional bundle effect on the hair cell response by varying the number of cilia forced. These varying forcing conditions affected the hair cell response.