Molecular and physiological bases of the K+ circulation in the mammalian inner ear.

Endolymph, the extracellular solution in cochlea, contains 150 mM K(+) and exhibits a potential of approximately +80 mV relative to neighboring extracellular spaces. This unique situation, essential for hearing, is maintained by K(+) circulation from perilymph to endolymph through the cochlear lateral wall. Recent studies have identified ion-transport molecules involved in the K(+) circulation and their pathophysiological relevance.