A virtual hair cell: II. Evaluation of mechanoelectric transduction parameters

¹ Virginia Tech

^* To whom correspondence should be addressed. E-mail: jcotton{at}vt.edu.

Submitted on March 14, 2006
Revised on June 13, 2006
Accepted on 17 November 2006

	Abstract

The virtual hair cell we have proposed utilizes a set of parameters related to its mechanoelectric transduction. In this paper, 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 (TLA) on the channel. The critical tension is the tension in the TLA 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; 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 3-D bundle effect on the hair cell response by varying the number of cilia forced. These varying forcing conditions affected the hair cell response.

Key Words: finite element, hair cell, mechanoelectric transduction, sensitivity