Cochlear Hair Cell Electrochemistry: Mechanisms for Bidirectional Transduction

摘要

A unique division of labor exists within the mammalian cochlea where electrochemical energy generated by one organ (the stria vascularis) is used by cells in another organ (the organ of Corti). Specifically, outer hair cells carry out bi-directional transduction (mechano-electrical and electro-mechanical) utilizing the energy of the endocochlear potential. We have measured intracochlear potential gradients in vivo to examine the fine structure of cochlear ionic currents both in silence and in response to acoustic stimulation Brownell, W.E., Manis, P.B., & Zidanic, M., J. Acoust Soc. Am., 74:792-800 (1983); Brownell, W.E. Zidanic, M., & Spirou, G.A., Neurobiology of Hearing: The Cochlear, R.A. Altschuler, et.al. (Eds), Raven Press, 91-107 (1986). The spatial profiles of potential gradient magnitude (as large as 20 mV/mm) and direction are compatible with a flow of cations (largely potassium) in a local circuit that is driven by an ionic pump in stria vascularis. The standing current (the 'silent current') is large and can be measured in all three chambers of the mammalian ear.