Calcium-activated potassium channel (KCa channel) (KCa channel)

Calcium-activated potassium (KCa) channels are a diverse family of ion channels that open in response to increases in intracellular calcium concentrations, allowing potassium ions to flow out of the cell. This efflux leads to membrane hyperpolarization, which serves as a critical feedback mechanism to limit further calcium entry and dampen cellular excitability (IUPHAR/BPS Guide to PHARMACOLOGY, 2023). These channels are categorized into three main subfamilies based on their conductance: large (BK), intermediate (IK), and small (SK) conductance channels (UniProt, 2024). They play vital roles in physiological processes such as smooth muscle relaxation, neurotransmitter release, and the regulation of cardiac rhythm (StatPearls, 2023). Dysregulation of KCa channels is implicated in various pathologies, including hypertension, epilepsy, and certain cancers, making them attractive therapeutic targets (Nature Reviews Drug Discovery, 2018). Pharmacological modulation involves both activators to reduce excitability and inhibitors to enhance it, though achieving tissue specificity remains a significant challenge in drug development (PubMed, 2022).

Other names

KCa channelsBK channelsIK channelsSK channelsMaxi-K channelsSlo1Gardos channelKCNMA1KCNN1KCNN2KCNN3KCNN4KCa1.1KCa2.1KCa2.2KCa2.3KCa3.1Ca2+-activated K+ channels

Modulation of potassium ion efflux through calcium-dependent gating to regulate cellular membrane potential and excitability (IUPHAR/BPS Guide to PHARMACOLOGY, 2023).