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). Activated by N-ethylmaleimide (NEM). Inhibited by furosemide, DIDS and bumetanide. The inhibition is much stronger in the presence of 50 mM K(+) in the uptake medium. Inhibited by DIOA. Inhibited by WNK3. Homomultimer and heteromultimer with other K-Cl cotransporters. Detected in muscle, brain, lung, heart and kidney. Belongs to the SLC12A transporter family.