Physiological oxygen-sensing machinery in pulmonary arterial smooth muscle cells

The physiological oxygen-sensing machinery in pulmonary arterial smooth muscle cells (PASMCs) is a specialized multi-component system that mediates hypoxic pulmonary vasoconstriction (HPV) (Waypa et al., 2016). This mechanism is essential for matching ventilation with perfusion in the lungs by redirecting blood flow away from hypoxic alveoli to better-oxygenated regions (Sommer et al., 2017). The machinery typically involves mitochondria acting as the primary sensors, where changes in oxygen tension alter the production of reactive oxygen species (ROS) or the redox state, specifically the NADH/NAD+ ratio (Archer et al., 2008). These mitochondrial signals subsequently modulate the activity of redox-sensitive voltage-gated potassium (Kv) channels, such as Kv1.5 and Kv2.1 (Dunham-Snary et al., 2017). Inhibition of these Kv channels during hypoxia leads to membrane depolarization and the opening of L-type voltage-gated calcium channels, resulting in an influx of calcium that triggers smooth muscle contraction (Waypa et al., 2016). In chronic disease states like pulmonary arterial hypertension (PAH), this machinery becomes dysfunctional, often characterized by the downregulation of Kv channels and a shift toward a glycolytic mitochondrial phenotype (Archer et al., 2008). Therapeutic strategies targeting this machinery include calcium channel blockers to prevent contraction and experimental agents like dichloroacetate to restore mitochondrial function (Dunham-Snary et al., 2017). Understanding this machinery is crucial for developing selective treatments that can alleviate pulmonary hypertension without causing systemic side effects.

Other names

Mitochondria-ROS-Kv channel axisOxygen-sensing signalosomeHypoxic pulmonary vasoconstriction (HPV) machineryPASMC oxygen sensor

The machinery operates through a mitochondria-to-ion channel signaling pathway where hypoxia decreases mitochondrial ROS production or alters the NADH/NAD+ ratio, leading to the closure of voltage-gated potassium channels (Kv1.5, Kv2.1) (Archer et al., 2008). This closure causes membrane depolarization, which activates L-type voltage-gated calcium channels, increasing intracellular calcium and inducing vasoconstriction (Waypa et al., 2016).