Résumé
VOLTAGE-ACTIVATED sodium currents (INa) in vestibular ganglion neurones acutely isolated from postnatal mice were investigated using the whole-cell configuration of the patch-clamp technique. Under recording conditions designed to allow the complete isolation of INa depolarizations from a holding potential of −80 mV revealed a fast inactivating inward current which was activated around −60 mV and exhibited maximum peak current around −30 mV. This current was eliminated when the cells were perifused with a Na-free solution and almost totally blocked by application of 100 nM tetrodotoxin (TTX). These properties identify this inward current as TTX-sensitive INa. The half-maximum activation potential of INa was −46 mV and its half-maximum inactivation potential was −69 mV. This is the first report of voltage-activated sodium currents in vestibular primary neurones.