A molecular mechanism for electrical tuning of cochlear hair cells

Cochlear frequency selectivity in lower vertebrates arises in part from electrical tuning intrinsic to the sensory hair cells. The resonant frequency is determined largely by the gating kinetics of calcium-activated potassium (BK) channels encoded by the slo gene. Alternative splicing of slo from chick cochlea generated kinetically distinct BK channels. Combination with accessory β subunits slowed the gating kinetics of α spice variants but preserved relative differences between them. In situ hybridization showed that the β subunit is preferentially expressed by low-frequency (apical) hair cells in the avian cochlea. Interaction of β with α splice variants could provide the kinetic range needed for electrical tuning of cochlear hair cells.