Mediates electroneutral potassium-chloride cotransport when activated by cell swelling. May mediate K+ uptake into Deiters' cells in the cochlea and contribute to K+recycling in the inner ear. Important for the survival of cochlear outer and inner hair cells and the maintenance of the organ of Corti. May be required for basolateral Cl-extrusion in the kidney and contribute to renal acidification (By similarity).