Hair cells fast adaptation

Transduction channels do not remain open, even if a deflection is maintained using two independent processes, the hair cell adapts to a sustained mechanical stimulus [12]. Rapid channel reclosure (sometimes called fast adaptation) occurs on a time-scale of a few milliseconds... 

FIGURE 51-4 Fast adaptation by hair cells. After a positive (excitatory) deflection, Ca2+ enters transduction channels, binds to a site at the channel, yanking the channel shut. The movement of the channel s gate increases tension in the tip link, and the bundle is moved in the negative direction. 

An alternative view of the source of cochlear amplification is that it arises in the OHC s bundles of stereocilia. The stereocilia bundle is composed of many actin filaments, and the kinocilium containing mainly axonemal microtubules. At least three types of actin-dependent molecular motor proteins are expressed in the stereocilia and are involved in adaptation of the hair cell MET channels myosin 15A (Rzadzinska et al., 2004), myosin 7A (Kros et al., 2002), and myosin 1C (Gillespie and Cyr, 2004). Many studies have shown that fast adaptation of MET channels can amplify the oscillation of hair bundles in the nonmammalian auditory... 

Ricci AJ, Crawford AC, Fettiplace R. 2000. Active hair bundle motion linked to fast transducer adaptation in auditory hair cells. J Neurosci 20 7131-7142. 

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