Properties of voltage-gated sodium channels in developing auditory neurons of the mouse in vitro.
OBJECTIVE
To investigate the properties of voltage-gated sodium (Na+) channels in developing auditory neurons during early postnatal stages in the mammalian central nervous system.


METHODS
Using the whole-cell voltage-clamp technique, we have studied changes in the electrophysiological properties of Na+ channels in the principal neurons of the medial nucleus of the trapezoid body (MNTB).


RESULTS
We found that MNTB neurons already express functional Na+ channels at postnatal day 1 (P1), and that channel density begins to increase at P5 when the neurons receive synaptic innervation and reach its maximum (approximately 3 fold) at P11 when functional hearing onsets. These changes were paralleled by an age-dependent acceleration in both inactivation and recovery from inactivation. In contrast, there was very little alteration in the voltage-dependence of inactivation.


CONCLUSIONS
These profound changes in the properties of voltage-gated Na+ channels may increase the excitability of MNTB neurons and enhance their phase-locking fidelity and capacity during high-frequency synaptic transmission.
Ming
Gui
G
Department of Cardiology, the First Affiliated Hospital, Nanjing Medical University, Nanjing 210029.
Wang
Lu-Yang
LY
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D001306:Auditory Pathways / Q000254:growth & development / Q000502:physiology*; D001933:Brain Stem / Q000166:cytology / Q000254:growth & development / Q000502:physiology*; D017626:Cochlear Nucleus / Q000254:growth & development / Q000502:physiology*; D004594:Electrophysiology; D015640:Ion Channel Gating / Q000502:physiology; D051379:Mice; D009474:Neurons / Q000502:physiology; D018408:Patch-Clamp Techniques; D015222:Sodium Channels / Q000502:physiology*
D015222:Sodium Channels