Voltage-gated cardiac potassium channel (Kv)

Voltage-gated cardiac potassium channels are a superfamily of transmembrane proteins essential for the electrical activity of the heart, mediating the efflux of potassium ions from myocytes to drive the repolarization phase of the action potential (NIH, 1998; AHA, 1998). This group includes several functionally distinct currents, such as the transient outward current (Ito), the ultra-rapid delayed rectifier (IKur), and the rapid (IKr) and slow (IKs) delayed rectifiers, which are mediated by specific alpha-subunits like Kv4.3, Kv1.5, Kv11.1 (hERG), and Kv7.1 (Guide to Pharmacology; AHA, 1998). These channels are primary targets for Class III antiarrhythmic drugs, such as amiodarone and dofetilide, which prolong the action potential duration and refractoriness to treat arrhythmias like atrial fibrillation (Nature Reviews Drug Discovery, 2009; NIH, 2009). However, unintended inhibition of these channels—most notably the hERG channel—is a major safety concern in drug development due to the risk of acquired long QT syndrome and life-threatening ventricular arrhythmias like Torsades de Pointes (NIH, 2009; Cancers, 2023). Mutations in the genes encoding these channels are also linked to congenital channelopathies, including Long QT and Brugada syndromes (NIH, 2013; AHA, 1998). The diversity of these channels allows for fine-tuning of the action potential shape across different regions of the heart, such as the atria and ventricles (AHA, 1998). Pharmacological modulation can involve either direct pore blockade or alteration of gating kinetics, such as activation or inactivation rates (Nature Reviews Drug Discovery, 2009).

Other names

Cardiac voltage-gated potassium channelCardiac Kv channelDelayed rectifier potassium channelTransient outward potassium channelVoltage-gated cardiac K+ channel

Inhibition of potassium ion efflux through the channel pore, leading to prolongation of the cardiac action potential and the effective refractory period.