Mechano-electrical transduction of the hair cell.

Auditory and vestibular inputs are applied to the hair cell hair bundle as mechanical energy, and are transduced into electrical energy by gating ion channels, most likely at the base of the hair bundle. The mechano-electrical transduction channel has a unitary conductance of 50 pS and has a broad selectivity to monovalent cations and to divalent cations. Ca ions are the most permeable through the channel. The angular displacement of the hair bundle is the primary gating factor. However, we still do not know the exact linkage between the angular displacement and the channel gating. Circumstantial evidence indicates a possibility of the direct gating of channels by the membrane deformation itself. ATP and cholinergic muscarinic receptors likely mediate the inhibitory efferent innervation to the hair cell.