 The Nav1.7 channel amplifies these membrane depolarizations, and when the membrane potential difference reaches a specific threshold, the neuron fires.In sensory neurons, multiple voltage-dependent sodium currents can be differentiated by their voltage dependence and by sensitivity to the voltage-gated sodium-channel blocker tetrodotoxin.The Nav1.7 channel produces a rapidly activating and inactivating current which is sensitive to the level of tetrodotoxin.