CHANNELS, RECEPTORS, AND ELECTRICAL SIGNALING |
A virtual hair cell: I. Addition of gating spring theory
into a 3-D bundle mechanical model
Jong-Hoon Nam 1, John R. Cotton 1* and Wally Grant 1
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
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Abstract |
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We have developed a virtual hair cell that simulates hair cell mechano-electrical transduction (MET) in the turtle utricle. This study combines a full 3-D hair bundle mechanical model with a gating spring theory. Previous mathematical models represent the hair bundle with a single degree of freedom system which, we have argued, cannot fully explain hair bundle mechanics. In our computer model, the tip link tension and fast adaptation modulator kinetics determine the opening and closing of each channel independently. We observed the response of individual transduction channels with our presented model. The simulated results showed three features of hair cells in vitro: First, a transient rebound of the bundle tip appeared when fast adaptation dominated the dynamics. Second, the dynamic stiffness of the bundle was minimized when the response-displacement (I-X) curve was steepest. Third, the hair cell showed "polarity", i.e. activation decreased from a peak to zero as the forcing direction rotated from the excitatory to inhibitory direction.
Key Words:
finite element, hair cell, mechanoelectric transduction, sensitivity
