Mechanoelectrical transduction of the chick hair cell

Abstract

Hair cells transduce mechanical energy applied to the apical hair bundle into an electrical signal, i.e., the transduction potential, through gating of mechanically gated ion channels (m-e.t. channel). The gate demonstrates sigmoidal displacement versus response relationship irrespective of the variation in the hair bundle's length (from 7 to 30μm), as long as the stimulus is applied to the hair bundle at a fixed height from its insertion into the apical surface of the cell. The angular displacement of the hair bundle could therefore be a primary factor that determines the gating of the m-e.t. channel. The channel demonstrates strong selectivity to divalent cations, particularly to Ca ions, over monovalent cations. Mn is one of the permeants through the channel. Fura-2 fluorescence is modified by Ca and Mn ions permeated through m-e.t. channel, and these ions produce a localized peak and a localized depression, respectively, in the 340/380-nm fluorescence ratio images during mechanical stimulation in the vicinity of the hair bundle's insertion into the apical surface of the cell. This might be indicating the site of the mechanoelectrical transduction.