Cardiac Transient Outward Potassium Channel (I_to)

The cardiac transient outward potassium channel is responsible for generating the transient outward potassium current (I_to) in heart muscle cells (cardiomyocytes). This current plays a crucial role during phase 1 of the cardiac action potential, contributing to the initial rapid repolarization that follows depolarization. The movement of potassium ions (K+) from inside to outside the cell through these channels causes a brief outward current that helps shape the action potential waveform and influences subsequent calcium entry and contraction. The fast component (I_to,f) is formed by Kv4.2 (KCND2) and/or Kv4.3 (KCND3) alpha subunits, often co-assembled with accessory proteins such as KChIP2 and DPP6. The slow component (I_to,s) is composed primarily of Kv1.4 (KCNA4) subunits. Reduced I_to,f density is observed in failing hearts and chronic atrial fibrillation; it also plays a role in arrhythmogenic conditions like Brugada syndrome.

Other names

ItoIto1Transient Outward Potassium Current

Potassium channel blockade