The role of potassium recirculation in cochlear amplification.

PURPOSE OF REVIEW Normal cochlear function depends on maintaining the correct ionic environment for the sensory hair cells. Here we review recent literature on the cellular distribution of potassium transport-related molecules in the cochlea. RECENT FINDINGS Transgenic animal models have identified novel molecules essential for normal hearing and support the idea that potassium is recycled in the cochlea. The findings indicate that extracellular potassium released by outer hair cells into the space of Nuel is taken up by supporting cells, that the gap junction system in the organ of Corti is involved in potassium handling in the cochlea, that the gap junction system in stria vascularis is essential for the generation of the endocochlear potential, and that computational models can assist in the interpretation of the systems biology of hearing and integrate the molecular, electrical, and mechanical networks of the cochlear partition. Such models suggest that outer hair cell electromotility can amplify over a much broader frequency range than expected from isolated cell studies. SUMMARY These new findings clarify the role of endolymphatic potassium in normal cochlear function. They also help current understanding of the mechanisms of certain forms of hereditary hearing loss.