Elementary properties of CaV1.3 Ca2+ channels expressed in mouse cochlear inner hair cells


Mammalian cochlear inner hair cells (IHCs) are specialized to process developmental signals during immature stages and sound stimuli in adult animals. These signals are conveyed onto auditory afferent nerve fibres. Neurotransmitter release at IHC ribbon synapses is controlled by L-type Ca(V)1.3 Ca(2+) channels, the biophysics of which are still unknown in native mammalian cells. We have investigated the localization and elementary properties of Ca(2+) channels in immature mouse IHCs under near-physiological recording conditions. Ca(V)1.3 Ca(2+) channels at the cell pre-synaptic site co-localize with about half of the total number of ribbons present in immature IHCs. These channels activated at about 70 mV, showed a relatively short first latency and weak inactivation, which would allow IHCs to generate and accurately encode spontaneous Ca(2+) action potential activity characteristic of these immature cells. The Ca(V)1.3 Ca(2+) channels showed a very low open probability (about 0.15 at 20 mV: near the peak of an action potential). Comparison of elementary and macroscopic Ca(2+) currents indicated that very few Ca(2+) channels are associated with each docked vesicle at IHC ribbon synapses. Finally, we found that the open probability of Ca(2+) channels, but not their opening time, was voltage dependent. This finding provides a possible correlation between presynaptic Ca(2+) channel properties and the characteristic frequency/amplitude of EPSCs in auditory afferent fibres.

DOI: 10.1113/jphysiol.2009.181917

Extracted Key Phrases

Citations per Year

333 Citations

Semantic Scholar estimates that this publication has 333 citations based on the available data.

See our FAQ for additional information.

Cite this paper

@inproceedings{Zampini2010ElementaryPO, title={Elementary properties of CaV1.3 Ca2+ channels expressed in mouse cochlear inner hair cells}, author={Valeria Zampini and Stuart L Johnson and Christoph Franz and Neil D. Lawrence and Stefan Muenkner and Jutta Engel and Marlies Knipper and Jacopo Magistretti and Sergio Masetto and Walter Marcotti}, booktitle={The Journal of physiology}, year={2010} }