Distinct repriming and closed-state inactivation kinetics of Nav1.6 and Nav1.7 sodium channels in mouse spinal sensory neurons.

摘要: While large, myelinated dorsal root ganglion (DRG) neurons are capable of firing at high frequencies, small unmyelinated DRG typically display much lower maximum frequencies. However, the molecular basis for this difference has not been delineated. Because sodium currents in large exhibit rapid repriming (recovery from inactivation) kinetics and predominantly slow kinetics, it proposed that differences channels might contribute to determination repetitive properties neurons. A recent study demonstrated Nav1.7 expression is negatively correlated with conduction velocity cell size, while Nav1.6 voltage-gated channel implicated as predominant isoform present nodes Ranvier fibres. Therefore we characterized compared functional properties, including repriming, recombinant expressed mouse Both generated fast-activating fast-inactivating currents. However recovery inactivation was significantly faster (approximately 5-fold -70 mV) than The also native tetrodotoxin-sensitive recorded spinal sensory neurons, but similar Development closed-state Our results indicate can be tuned by regulating different isoforms have distinct kinetics.