Voltage-gated sodium channel (Nav channel) (Nav channel)

Voltage-gated sodium channels (Nav channels) are essential transmembrane proteins that mediate the rapid influx of sodium ions into excitable cells, a process fundamental to the initiation and propagation of action potentials [2, 8]. These channels are composed of a large, pore-forming alpha subunit (isoforms Nav1.1 through Nav1.9) and one or more auxiliary beta subunits that regulate channel kinetics, trafficking, and cell-surface expression [3, 4]. The Nav1.5 isoform is the primary cardiac sodium channel, responsible for the rapid depolarization phase of the heart's electrical cycle, while other isoforms are specialized for the central nervous system (Nav1.1, 1.2, 1.3, 1.6), skeletal muscle (Nav1.4), and peripheral pain signaling (Nav1.7, 1.8, 1.9) [7, 10, 12]. Mutations in the genes encoding these channels (SCN family) lead to various channelopathies, including cardiac arrhythmias like Long QT Syndrome Type 3 and Brugada Syndrome, as well as epilepsy and chronic pain conditions [2, 9, 10]. Pharmacologically, Nav channels are the targets of several major drug classes, including local anesthetics, Class I antiarrhythmics, and anticonvulsants, which typically function by blocking the ion-conducting pore in a state-dependent manner [1, 6, 7]. Modern drug discovery efforts are increasingly focused on developing isoform-selective inhibitors to minimize off-target effects, particularly for treating chronic pain without affecting cardiac or central nervous system function [7, 13].

Other names

Voltage-dependent sodium channel [8]Sodium channel alpha subunit [3, 4]Nav1.1-1.9 [3, 8]SCN family [3, 9]Voltage-gated sodium channels – cardiac and other isoformsSodium channel protein type 1 subunit alpha (SCN1A) [9]Sodium channel protein type 2 subunit alpha (SCN2A) [9]Sodium channel protein type 3 subunit alpha (SCN3A) [9]Sodium channel protein type 4 subunit alpha (SCN4A) [10]Sodium channel protein type 5 subunit alpha (SCN5A) [10, 12]Sodium channel protein type 8 subunit alpha (SCN8A) [9, 16]Sodium channel protein type 9 subunit alpha (SCN9A) [7, 11]Sodium channel protein type 10 subunit alpha (SCN10A) [10, 12]Sodium channel protein type 11 subunit alpha (SCN11A) [11, 13]

Voltage-gated sodium channel blockers primarily inhibit the influx of sodium ions by binding to a receptor site within the channel's pore, often involving the S6 segments of domains III and IV [1, 2]. Many of these drugs exhibit state-dependent or use-dependent block, meaning they have a higher affinity for the channel when it is in the open or inactivated state, which allows them to selectively suppress high-frequency electrical activity associated with arrhythmias or seizures while sparing normal tissue function [6, 7]. Some agents also act as gating modifiers by binding to the voltage-sensing domains to alter the channel's response to membrane potential changes [1, 6].