Potassium large conductance calcium-activated channel subfamily M alpha member 1 (KCNMA1) (KCNMA1)

Potassium large conductance calcium-activated channel subfamily M alpha member 1 (KCNMA1), also known as the BK or MaxiK channel, is a voltage-gated potassium channel uniquely sensitive to intracellular calcium concentrations (UniProt: Q12791). It serves as a key regulator of cellular excitability by coupling changes in intracellular calcium and membrane potential to potassium efflux, which induces hyperpolarization (PubMed: 30531970). This channel is vital for physiological processes including the relaxation of vascular and visceral smooth muscle, the shaping of neuronal action potentials, and the modulation of neurotransmitter release (NCBI Gene: 3778). Dysregulation or mutations in the KCNMA1 gene are associated with a spectrum of disorders such as epilepsy, paroxysmal dyskinesia, and hypertension (PubMed: 29133745). Pharmacological modulation of the BK channel via openers or blockers offers therapeutic potential for treating cardiovascular, respiratory, and neurological conditions, though tissue specificity remains a significant hurdle (PubChem).

Other names

BK channelMaxiK channelSlo1KCa1.1Calcium-activated potassium channel subunit alpha-1hSloK(VCA)alphaSlo

The primary mechanism of action for drugs targeting this channel involves the modulation of its open probability. Openers (activators) like NS1619 and BMS-204352 shift the voltage-dependence of activation toward more negative potentials, facilitating potassium efflux which leads to membrane hyperpolarization and reduced cellular excitability. Conversely, blockers (inhibitors) like paxilline and iberiotoxin physically occlude the pore or interfere with the gating mechanism, preventing potassium efflux and thereby maintaining or increasing cellular excitability and calcium influx.