Potassium channel subfamily K member ACh (IKACh)

The potassium channel subfamily K member ACh, commonly referred to as IKACh, is a cardiac potassium ion channel that plays a crucial role in regulating heart rate. It is specifically activated by acetylcholine through muscarinic receptors and is responsible for the acetylcholine-dependent slowing of the heart rate. It is a heteromultimeric complex composed of GIRK1 and CIR/GIRK4 subunits. Activation leads to an increase in potassium conductance across the cell membrane, resulting in hyperpolarization and decreased excitability of cardiac pacemaker cells. Dysfunctions can contribute to arrhythmias or abnormal heart rates due to impaired parasympathetic control.

Other names

GIRK1/Kir3.1 + CIR/GIRK4/Kir3.4G-protein-gated inwardly rectifying potassium channelAcetylcholine-activated potassium channel

Activation of muscarinic M2 receptors by acetylcholine leads to G protein activation and subsequent direct binding of Gβγ-subunits to the IKACh channel, causing channel opening and increased potassium conductance.