Electrical properties and functional expression of ionic channels in cochlear inner hair cells of mice lacking the alpha10 nicotinic cholinergic receptor subunit

MARIA EUGENIA GÓMEZ CASATI; CAROLINA WEDEMEYER; JULIÁN TARANDA; M. MARCELA LIPOVSEK; VIVIANA DALAMON; ANA BELÉN ELGOYHEN; ELEONORA KATZ

Journal of the Association for Research in Otorayngology

Springer

Lugar: New York; Año: 2009 vol. 10 p. 221 - 232

1438-7573

Cochlear inner hair cells (IHCs) release neurotrans-mitter onto afferent auditory nerve fibers in responseto  sound  stimulation.  During  early  development,synaptic  transmission  is  triggered  by  spontaneousCa2+   spikes  which  are  modulated  by  an  efferentcholinergic  innervation  to  IHCs.  This  synapse  isinhibitory  and  mediated  by  the  alpha9alpha10  nicotiniccholinergic  receptor  (nAChR).  After  the  onset  ofhearing,  large-conductance  Ca2+-activated  K+   chan-nels are acquired and both the spiking activity and theefferent  innervation  disappear  from  IHCs.  In  thiswork, we studied the developmental changes in themembrane  properties  of  cochlear  IHCs  from  alpha10nAChR  gene  (Chrna10)  ?knockout?  mice.  Electro-physiological  properties  of  IHCs  were  studied  bywhole-cell recordings in acutely excised apical turnsof the organ of Corti from developing mice. Neitherthe spiking activity nor the developmental functionalexpression of voltage-gated and/or calcium-sensitiveK+   channels  is  altered  in  the  absence  of  the  alpha10nAChR subunit. The present results show that the alpha10nAChR  subunit  is  not  essential  for  the  correctestablishment of the intrinsic electrical properties ofIHCs during development.