bk channels mediate cholinergic inhibition of high frequency cochlear hair cellsbk通道调节胆碱能抑制高频耳蜗毛细胞.pdfVIP

BK Channels Mediate Cholinergic Inhibition of High Frequency Cochlear Hair Cells 1 2 1 2 Eric Wersinger , Will J. McLean , Paul A. Fuchs , Sonja J. Pyott * 1 Department of Otolaryngology Head and Neck Surgery, Center for Hearing and Balance, and Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America, 2 Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina, United States of America Abstract Background: Outer hair cells are the specialized sensory cells that empower the mammalian hearing organ, the cochlea, with its remarkable sensitivity and frequency selectivity. Sound-evoked receptor potentials in outer hair cells are shaped by both voltage-gated K+ channels that control the membrane potential and also ligand-gated K+ channels involved in the cholinergic efferent modulation of the membrane potential. The objectives of this study were to investigate the tonotopic contribution of BK channels to voltage- and ligand-gated currents in mature outer hair cells from the rat cochlea. Methodology/Principal: Findings In this work we used patch clamp electrophysiology and immunofluorescence in tonotopically defined segments of the rat cochlea to determine the contribution of BK channels to voltage- and ligand- gated currents in outer hair cells. Although voltage and ligand-gated currents have been investigated previously in hair cells from the rat cochlea, little is known about their tonotopic distribution or potential contribution to efferent inhibition. We found that apical (low frequency) outer hair cells had no BK channel immunoreactivity and little or no BK current. In marked contrast, basal (high frequency)