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

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Valeria Zampini
Stuart Leigh Johnson
Christoph Franz
Neil D. Lawrence, University of Sheffield
Stefan Muenkner Jutta Engel
Marlies Knipper
Jacopo Magistretti
Sergio Masetto
Walter Marcotti

The Journal of Physiology 588, pp 187-189

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Abstract

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 CaV1.3 Ca2+ channels, the biophysics of which are still unknown in native mammalian cells. We have investigated the localization and elementary properties of Ca2+ channels in immature mouse IHCs under near-physiological recording conditions. CaV1.3 Ca2+ 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 relatively hyperpolarized membrane potentials (about -70 mV), showed a relatively short first latency and weak inactivation, which would allow IHCs to generate and accurately encode spontaneous Ca2+ action potential activity characteristic of these immature cells. The CaV1.3 Ca2+ 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 Ca2+ currents indicated that very few Ca2+ channels are associated with each docked vesicle at IHC ribbon synapses. Finally, we found that the open probability of Ca2+ channels, but not their opening time, was voltage dependent. This finding provides a possible correlation between presynaptic Ca2+ channel properties and the characteristic frequency/amplitude of EPSCs in auditory afferent fibres.


@Article{zampini-elementary09,
  title = 	 {Elementary properties of CaV1.3 Ca2+ channels expressed in mouse cochlear inner hair cells},
  journal =  	 {The Journal of Physiology},
  author = 	 {Valeria Zampini and Stuart Leigh Johnson and Christoph Franz and Neil D. Lawrence and Stefan Muenkner Jutta Engel and Marlies Knipper and Jacopo Magistretti and Sergio Masetto and Walter Marcotti},
  pages = 	 {187},
  year = 	 {2010},
  volume = 	 {588},
  month = 	 {00},
  edit = 	 {https://github.com/lawrennd//publications/edit/gh-pages/_posts/2010-01-01-zampini-elementary09.md},
  url =  	 {http://inverseprobability.com/publications/zampini-elementary09.html},
  abstract = 	 {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 CaV1.3 Ca2+ channels, the biophysics of which are still unknown in native mammalian cells. We have investigated the localization and elementary properties of Ca2+ channels in immature mouse IHCs under near-physiological recording conditions. CaV1.3 Ca2+ 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 relatively hyperpolarized membrane potentials (about -70 mV), showed a relatively short first latency and weak inactivation, which would allow IHCs to generate and accurately encode spontaneous Ca2+ action potential activity characteristic of these immature cells. The CaV1.3 Ca2+ 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 Ca2+ currents indicated that very few Ca2+ channels are associated with each docked vesicle at IHC ribbon synapses. Finally, we found that the open probability of Ca2+ channels, but not their opening time, was voltage dependent. This finding provides a possible correlation between presynaptic Ca2+ channel properties and the characteristic frequency/amplitude of EPSCs in auditory afferent fibres.},
  key = 	 {Zampini-elementary09},
  doi = 	 {10.1113/jphysiol.2009.181917},
  OPTgroup = 	 {}
 

}
%T Elementary properties of CaV1.3 Ca2+ channels expressed in mouse cochlear inner hair cells
%A Valeria Zampini and Stuart Leigh Johnson and Christoph Franz and Neil D. Lawrence and Stefan Muenkner Jutta Engel and Marlies Knipper and Jacopo Magistretti and Sergio Masetto and Walter Marcotti
%B 
%C The Journal of Physiology
%D 
%F zampini-elementary09
%J The Journal of Physiology	
%P 187--189
%R 10.1113/jphysiol.2009.181917
%U http://inverseprobability.com/publications/zampini-elementary09.html
%V 588
%X 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 CaV1.3 Ca2+ channels, the biophysics of which are still unknown in native mammalian cells. We have investigated the localization and elementary properties of Ca2+ channels in immature mouse IHCs under near-physiological recording conditions. CaV1.3 Ca2+ 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 relatively hyperpolarized membrane potentials (about -70 mV), showed a relatively short first latency and weak inactivation, which would allow IHCs to generate and accurately encode spontaneous Ca2+ action potential activity characteristic of these immature cells. The CaV1.3 Ca2+ 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 Ca2+ currents indicated that very few Ca2+ channels are associated with each docked vesicle at IHC ribbon synapses. Finally, we found that the open probability of Ca2+ channels, but not their opening time, was voltage dependent. This finding provides a possible correlation between presynaptic Ca2+ channel properties and the characteristic frequency/amplitude of EPSCs in auditory afferent fibres.
TY  - CPAPER
TI  - Elementary properties of CaV1.3 Ca2+ channels expressed in mouse cochlear inner hair cells
AU  - Valeria Zampini
AU  - Stuart Leigh Johnson
AU  - Christoph Franz
AU  - Neil D. Lawrence
AU  - Stefan Muenkner Jutta Engel
AU  - Marlies Knipper
AU  - Jacopo Magistretti
AU  - Sergio Masetto
AU  - Walter Marcotti
PY  - 2010/01/01
DA  - 2010/01/01	
ID  - zampini-elementary09	
SP  - 187
EP  - 189
DO  - 10.1113/jphysiol.2009.181917
UR  - http://inverseprobability.com/publications/zampini-elementary09.html
AB  - 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 CaV1.3 Ca2+ channels, the biophysics of which are still unknown in native mammalian cells. We have investigated the localization and elementary properties of Ca2+ channels in immature mouse IHCs under near-physiological recording conditions. CaV1.3 Ca2+ 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 relatively hyperpolarized membrane potentials (about -70 mV), showed a relatively short first latency and weak inactivation, which would allow IHCs to generate and accurately encode spontaneous Ca2+ action potential activity characteristic of these immature cells. The CaV1.3 Ca2+ 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 Ca2+ currents indicated that very few Ca2+ channels are associated with each docked vesicle at IHC ribbon synapses. Finally, we found that the open probability of Ca2+ channels, but not their opening time, was voltage dependent. This finding provides a possible correlation between presynaptic Ca2+ channel properties and the characteristic frequency/amplitude of EPSCs in auditory afferent fibres.
ER  -

Zampini, V., Johnson, S.L., Franz, C., Lawrence, N.D., Engel, S.M.J., Knipper, M., Magistretti, J., Masetto, S. & Marcotti, W.. (2010). Elementary properties of CaV1.3 Ca2+ channels expressed in mouse cochlear inner hair cells. The Journal of Physiology 588:187-189