Cardiac transient outward potassium current
Encyclopedia
Repolarization
In neuroscience, repolarization refers to the change in membrane potential that returns the membrane potential to a negative value after the depolarization phase of an action potential has just previously changed the membrane potential to a positive value. Repolarization results from the movement...
phase 1 of the cardiac action potential, and results from movement of potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
(K+) ions from the intracellular
Intracellular
Not to be confused with intercellular, meaning "between cells".In cell biology, molecular biology and related fields, the word intracellular means "inside the cell".It is used in contrast to extracellular...
to the extracellular space. It is complemented with Ito2 resulting from Cl- ions.
Mechanism
Ito1 is Ca2+Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
-independent and has been clearly demonstrated in myocytes from different cardiac regions and species. There are two kinetic variants of cardiac Ito1: fast Ito1, called Ito1,f, and slow Ito, called Ito1,s. Recent findings suggest that Ito1,f is formed by assembly of Kv4.2 (KCND2) and/or Kv4.3 (KCND3) subunits, while Ito1,s is composed of Kv1.4 (KCNA4) and possibly Kv1.7 (KCNA7) subunits. In addition, several regulatory subunits and pathways modulating the level and biophysical properties of cardiac Ito have been identified.