Figure 3.

Classification of K⁺ currents: General classification of the main cardiac K⁺ currents. The relatively new additions to the K⁺ channel family (Ca²⁺-activated K⁺ current [I_KCa] and 2-pore domain K⁺ current [I_K2p]) have not been grouped under this scheme. Most K⁺ currents are grouped according to the direction of their overall rectification property. In some instances, this may vary. With the inward rectifying K⁺ channels, the name refers to the unusual characteristic whereby net potassium flow is into the cell at potentials lower than the reversal potential where channel conductance is high. As the channel potential becomes more positive, channel conductance decreases. Net ion flow direction reverses at the reversal potential, meaning that net potassium flow is outward at potentials more positive than this. Therefore, at depolarized potentials, potassium loss from the cell is low as conductance through the channel is low.