Sodium channel protein type 5 subunit alpha (Na_v1.5) (Na_v1.5)

Sodium channel protein type 5 subunit alpha (Na_v1.5) is the predominant voltage-gated sodium channel in the human heart, encoded by the SCN5A gene (UniProt: P35498). It plays a fundamental role in cardiac physiology by mediating the rapid influx of sodium ions during the initial phase of the action potential, which triggers myocardial contraction and ensures synchronized electrical conduction (PubMed: 25587038). Dysregulation or genetic mutations in Na_v1.5 are associated with a spectrum of 'sodium channelopathies,' including Brugada syndrome and Long QT syndrome type 3, which can lead to sudden cardiac death (StatPearls: NBK537033). This channel is a major therapeutic target for Class I antiarrhythmic drugs, which are categorized by their binding kinetics and effects on the action potential duration (PubMed: 11976237). Beyond rhythm control, selective inhibition of the late sodium current is an emerging strategy for treating myocardial ischemia and heart failure to prevent calcium overload (PubMed: 15505131). However, the narrow therapeutic index of many Na_v1.5 blockers necessitates careful monitoring for potential proarrhythmic side effects or conduction disturbances.

Other names

SCN5ACardiac sodium channelVoltage-gated sodium channel type V alpha subunitHB1CDCD2CMD1ECMPD2ICCDLQT3PFHB1SSS1VF1SkM2

Class I antiarrhythmic drugs bind to the alpha subunit of the Na_v1.5 channel to inhibit the inward sodium current (I_Na), thereby slowing the rate of depolarization (Phase 0) and reducing conduction velocity. Some agents, such as ranolazine, specifically target the late sodium current (I_Na,L) to reduce intracellular sodium and calcium overload in ischemic conditions.