Large conductance calcium-activated potassium channel subunit alpha-1 (BKCa) (BKCa)

The Large conductance calcium-activated potassium channel (BKCa), primarily composed of the Large conductance calcium-activated potassium channel subunit alpha-1, is a high-conductance ion channel that integrates changes in intracellular calcium levels and membrane voltage to regulate cellular excitability [1]. In the peripheral carotid body, specifically within the oxygen-sensing glomus cells, BKCa channels play a pivotal role in the hypoxic ventilatory response by acting as downstream effectors of oxygen tension [2]. Under normal oxygen conditions, these channels are active and maintain the cell in a hyperpolarized state; however, hypoxia leads to channel inhibition, resulting in depolarization, calcium influx, and the release of neurotransmitters that stimulate the carotid sinus nerve to increase breathing [3]. Dysfunction of these channels is linked to various respiratory and cardiovascular pathologies, including sleep apnea and hypertension, where the chemoreflex is often hyper-sensitized [4]. Consequently, BKCa channels are significant therapeutic targets, with activators being explored to reduce pathological chemoreflex sensitivity and inhibitors potentially serving to stimulate respiration in cases of drug-induced respiratory depression [5].

Other names

BK channelMaxi-K channelKCa1.1Slo1Calcium-activated potassium channel subunit alpha-1KCNMA1

BKCa channel openers (activators) increase potassium conductance, leading to membrane hyperpolarization and reduced cellular excitability, which in the carotid body can dampen the hypoxic response [1, 5]. Conversely, BKCa channel blockers (inhibitors) cause membrane depolarization and increased neurotransmitter release, thereby enhancing the chemoreceptor-mediated respiratory drive [2, 3].