Vascular ATP-sensitive potassium channel (K_ATP) (K_ATP)

The vascular ATP-sensitive potassium (K_ATP) channel is a hetero-octameric protein complex that serves as a key regulator of vascular tone by coupling cellular metabolism to membrane excitability [PubMed, 2012]. In vascular smooth muscle, this channel is primarily composed of four pore-forming inward-rectifier potassium channel 6.1 (Kir6.1) subunits and four regulatory sulfonylurea receptor 2B (SUR2B) subunits [UniProt, 2024]. The channel's activity is modulated by the intracellular ATP/ADP ratio; a decrease in ATP or an increase in ADP, often occurring during hypoxia or metabolic stress, promotes channel opening [NCBI, 2010]. Opening of the K_ATP channel allows potassium ions to flow out of the cell, leading to membrane hyperpolarization and the subsequent closure of voltage-gated L-type calcium channels [StatPearls, 2023]. This reduction in calcium influx results in smooth muscle relaxation and vasodilation, effectively lowering peripheral vascular resistance and blood pressure [PubMed, 2017]. Pharmacologically, K_ATP channel openers like minoxidil and nicorandil are utilized in the management of refractory hypertension and angina, while gain-of-function mutations in the constituent subunits are the underlying cause of Cantú syndrome [NIH, 2021]. Conversely, non-selective sulfonylureas used in diabetes, such as glibenclamide, can inhibit these channels, potentially impacting vascular reactivity [PubChem, 2024].

Other names

KATP channelATP-sensitive inward rectifier potassium channelKir6.1/SUR2B complexKCNJ8/ABCC9 channelVascular smooth muscle KATP channel

Activation of the channel leads to potassium efflux and membrane hyperpolarization, which inhibits voltage-gated calcium channels, reducing intracellular calcium and causing vascular smooth muscle relaxation [StatPearls, 2023].