ATP-sensitive potassium channel containing sulfonylurea receptor 2 (KATP-SUR2)

ATP-sensitive potassium (KATP) channels containing the sulfonylurea receptor 2 (SUR2) subunit are critical metabolic sensors that link cellular energetic status to membrane excitability [1]. These channels are hetero-octameric complexes composed of four pore-forming inward-rectifier potassium channel subunits (typically Kir6.1 or Kir6.2) and four regulatory sulfonylurea receptor 2 subunits (SUR2A or SUR2B), which are encoded by the ABCC9 gene [2]. In vascular smooth muscle, the SUR2B isoform predominates and regulates vascular tone; its activation leads to potassium efflux, membrane hyperpolarization, and subsequent vasodilation [3]. In cardiac and skeletal muscle, the SUR2A isoform plays a vital role in protecting tissues against ischemic injury and metabolic stress by modulating action potential duration [4]. Pharmacological activation of these channels by potassium channel openers (KCOs), such as minoxidil and nicorandil, is utilized to treat refractory hypertension and angina pectoris [5]. Mutations in the ABCC9 gene are associated with genetic disorders like Cantu syndrome, which presents with hypertrichosis, cardiomegaly, and vascular abnormalities [6]. Sources: [1] Nichols CG. KATP channels as molecular sensors of cellular metabolism. Nature. 2006;440(7083):470-476. [2] UniProt KB. ABCC9 - ATP-binding cassette sub-family C member 9 (P54928). [3] Quayle JM, et al. ATP-sensitive and inward rectifier potassium channels in smooth muscle. Physiol Rev. 1997;77(4):1165-1232. [4] Zingman LV, et al. SUR2A: a therapeutic target for cardiovascular disease. Circ Res. 2002;91(11):935-943. [5] StatPearls. Potassium Channel Openers. Treasure Island (FL): StatPearls Publishing; 2023. [6] Harakalova M, et al. Dominant missense mutations in ABCC9 cause Cantu syndrome. Nat Genet. 2012;44(7):793-796.

Other names

SUR2-containing KATP channelABCC9-containing KATP channelVascular KATP channelCardiac KATP channelSulfonylurea receptor 2

Potassium channel openers (agonists) bind to the SUR2 subunit, increasing the probability of the channel being in an open state. This leads to an efflux of potassium ions, causing membrane hyperpolarization, which subsequently inhibits voltage-gated calcium channels, reduces intracellular calcium, and results in smooth muscle relaxation and vasodilation [3][5].