Potassium Channel - Types

Types

There are four major classes of potassium channels:

  • Calcium-activated potassium channel - open in response to the presence of calcium ions or other signalling molecules.
  • Inwardly rectifying potassium channel - passes current (positive charge) more easily in the inward direction (into the cell).
  • Tandem pore domain potassium channel - are constitutively open or possess high basal activation, such as the "resting potassium channels" or "leak channels" that set the negative membrane potential of neurons. When open, they allow potassium ions to cross the membrane at a rate that is nearly as fast as their diffusion through bulk water.
  • Voltage-gated potassium channel - are voltage-gated ion channels that open or close in response to changes in the transmembrane voltage.

The following table contains a comparison of the major classes of potassium channels with representative examples (for a complete list of channels within each class, see the respective class pages).

Potassium channel classes, function, and pharmacology.
Class Subclasses Function Blockers Activators
Calcium-activated
6T & 1P
  • BK channel
  • SK channel
  • inhibition following stimuli increasing intracellular calcium
  • charybdotoxin, iberiotoxin
  • apamin
  • 1-EBIO
  • NS309
  • CyPPA
Inwardly rectifying
2T & 1P
  • ROMK (Kir1.1)
  • recycling and secretion of potassium in nephrons
  • Nonselective: Ba2+, Cs+
  • none
  • GPCR regulated (Kir3.x)
  • mediate the inhibitory effect of many GPCRs
  • GPCR antagonists
  • ifenprodil
  • GPCR agonists
  • ATP-sensitive (Kir6.x)
  • close when ATP is high to promote insulin secretion
  • glibenclamide
  • tolbutamide
  • diazoxide
  • pinacidil
Tandem pore domain
4T & 2P
  • TWIK (TWIK-1, TWIK-2, KCNK7)
  • TREK (TREK-1, TREK-2, TRAAK)
  • TASK (TASK-1, TASK-3, TASK-5)
  • TALK (TASK-2, TALK-1, TALK-2)
  • THIK (THIK-1, THIK-2)
  • TRESK
  • Contribute to resting potential
  • bupivacaine
  • quinidine
  • halothane
Voltage-gated
6T & 1P
  • hERG (Kv11.1)
  • KvLQT1 (Kv7.1)
  • action potential repolarization
  • limits frequency of action potentials (disturbances cause dysrhythmia)
  • tetraethylammonium
  • 4-aminopyridine
  • dendrotoxins (some types)
  • retigabine (Kv7)

Read more about this topic:  Potassium Channel

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