What is IKr and IKs?
The 2 components of the delayed rectifier potassium current, IKr (rapid) and IKs (slow), play a dominant role in the repolarization of the action potential and are important determinants of its duration. Results demonstrate the importance of IKs density variations in heterogeneity of repolarization.
What happens if K+ channels are blocked?
The primary role of potassium channels in cardiac action potentials is cell repolarization. Therefore, blocking these channels slows (delays) repolarization, which leads to an increase in action potential duration and an increase in the effective refractory period (ERP).
What are a-type potassium channels?
A-type voltage-gated potassium (Kv) channels are major regulators of neuronal excitability that have been mainly characterized in the central nervous system.
What is IKr potassium?
Human ether-a-go-go-related gene (hERG) potassium channels conduct the rapid component of the delayed rectifier potassium current, IKr, which is crucial for repolarization of cardiac action potentials. Moderate hERG blockade may produce a beneficial class III antiarrhythmic effect.
What is IKr cardiac?
The rapid delayed rectifier (IKr) channel is important for cardiac action potential repolarization. Suppressing IKr function, due to either genetic defects in its pore-forming subunit (hERG) or adverse drug effects, can lead to long-QT (LQT) syndrome that carries increased risk of life-threatening arrhythmias.
How do potassium channels work?
Potassium Channels K+ channels are membrane proteins that allow rapid and selective flow of K+ ions across the cell membrane, and thus generate electrical signals in cells. Upon changes in transmembrane potential, these channels open and allow passive flow of K+ ions from the cell to restore the membrane potential.
How does potassium ion channel work?
Potassium channels allow K+ ions to easily diffuse through their pores while effectively preventing smaller Na+ ions from permeation. The ability to discriminate between these two similar and abundant ions is vital for these proteins to control electrical and chemical activity in all organisms.
What are potassium channel activators?
Potassium channels activators (PCA) are drugs which open or prolong the open state duration of potassium channels. Hence they promote potassium efflux, hyperpolarize the cell membrane, thus preventing intracellular penetration of calcium through the voltage-dependent calcium channels.
What voltage opens potassium channels?
Voltage-gated potassium channels are the largest ion channel family in the human genome encoding 40 voltage-gated K+ channels (KV), which have diverse physiological functions ranging from repolarization action potentials, setting membrane potential, dictating the duration or frequency of action potential, to modulation …
What voltage do potassium channels close?
Potassium ions reach equilibrium when the membrane voltage is below −70 mV, so a period of hyperpolarization occurs while the K+ channels are open. Those K+ channels are slightly delayed in closing, accounting for this short overshoot.