Smooth muscle ATP-sensitive potassium channel (K-ATP channel) (K-ATP channel)

The smooth muscle ATP-sensitive potassium (K-ATP) channel is a hetero-octameric protein complex typically composed of four inwardly rectifying potassium channel 6.1 (Kir6.1) subunits and four sulfonylurea receptor 2B (SUR2B) subunits (Source: UniProt P48541, O00559). These channels act as metabolic sensors, coupling the intracellular ATP/ADP ratio to membrane excitability; a decrease in ATP or an increase in ADP triggers channel opening (Source: PubMed PMID: 15556826). In vascular smooth muscle, activation of K-ATP channels leads to potassium efflux and membrane hyperpolarization, which inhibits voltage-gated calcium channels and reduces calcium influx, ultimately promoting vasodilation (Source: StatPearls, \"Potassium Channel Openers\"). This mechanism is essential for regulating systemic blood pressure and local blood flow in response to metabolic stress or pharmacological agents (Source: PubMed PMID: 22503554). Pharmacologically, these channels are targeted by potassium channel openers like minoxidil and nicorandil to treat severe hypertension and angina, while mutations in the encoding genes (KCNJ8 and ABCC9) are linked to Cantu syndrome (Source: NIH Genetic and Rare Diseases Information Center). Beyond the vasculature, these channels are also found in other smooth muscle tissues, such as the bladder and bronchi, where they modulate contractility (Source: PubMed PMID: 11159014).

Other names

K-ATP channelATP-dependent potassium channelKir6.1/SUR2B complexVascular K-ATP channelInwardly rectifying potassium channel 6.1/Sulfonylurea receptor 2B complex

Activation of the channel by potassium channel openers (KCOs) increases the open-state probability, leading to potassium efflux, membrane hyperpolarization, and subsequent relaxation of smooth muscle (Source: PubMed PMID: 10428313).