KCNJ10 Potassium Channel Knockout Abolishes Endocochlear Potential

Stria vascularis of the cochlea generates the endocochlear potential(EP) and secretes potassium into endolymph. K+ is the main chargecarrier of transduction current and the endocochlear potential the maindriving force for the sensory transduction that leads to hearing. Striavascularis consists of two barriers, marginal cells that secrete potassiumand basal cells that are coupled via gap junctions to intermediate cells.KCNJ10 (Kir4.1) was expressed on the cell membrane of strialintermediate cells. In our study, mice lacking the KCNJ10 (Kir4.1) K+channel in strial intermediate cells did not generate an endocochlearpotential. Cochlear endolymph volume and [K+] were reduced inhomozygous KCNJ10 knockout mice. In contrast, vestibulartransepithelial potential (UP), endolymph [K+] and volume were normal inhomozygous KCNJ10 knockout mice. These findings establish that theKCNJ10 K+ channel provides the molecular mechanism for generation ofthe endocochlear potential. KCNJ10 is also a limiting pathway for K*secretion.