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A ‘calcium capacitor’ shapes cholinergic inhibition of cochlear hair cells
Author(s) -
Fuchs Paul Albert
Publication year - 2014
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2013.267914
Subject(s) - postsynaptic potential , efferent , inhibitory postsynaptic potential , hair cell , cochlea , cholinergic , neuroscience , chemistry , calcium , microbiology and biotechnology , ionotropic effect , t type calcium channel , voltage dependent calcium channel , biophysics , biology , nmda receptor , receptor , biochemistry , afferent , organic chemistry
Efferent cholinergic neurons project from the brainstem to inhibit sensory hair cells of the vertebrate inner ear. This inhibitory synapse combines the activity of an unusual class of ionotropic cholinergic receptor with that of nearby calcium‐dependent potassium channels to shunt and hyperpolarize the hair cell. Postsynaptic calcium signalling is constrained by a thin near‐membrane cistern that is co‐extensive with the efferent terminal contacts. The postsynaptic cistern may play an essential role in calcium homeostasis, serving as sink or source, depending on ongoing activity and the degree of buffer saturation. Release of calcium from postsynaptic stores leads to a process of retrograde facilitation via the synthesis of nitric oxide in the hair cell. Activity‐dependent synaptic modification may contribute to changes in hair cell innervation that occur during development, and in the aged or damaged cochlea.