Voltage-gated Na+ channels (Nav) are essential for the generation of action potentials and for cell excitability1. Nav channels are activated in response to depolarization and selectively allow flow of Na+ ions. To date, nine Nav a subunits have been cloned and named Nav1.1-Nav1.94-5. The Nav channels are classified into two groups according to their sensitivity to Tetrodotoxin (TTX): TTX-sensitive (Nav1.1, Nav1.2, Nav1.3, Nav1.4, Nav1.6 and Nav1.7) and TTX-resistant (Nav1.5, Nav1.8 and Nav1.9)2-3. Mammalian sodium channels are heterotrimers, composed of a central, pore-forming α subunit and two auxiliary β subunits. The expression of the α subunit isoform is developmentally regulated and tissue specific. Na+ channels in the adult central nervous system and heart contain β1 through β4 subunits, whereas Na+ channels in adult skeletal muscle have only the β1 subunit.Nav1.1 is a tetrodotoxin-sensitive channel and is broadly expressed in neurons