title: Hypoxic Pulmonary Vasoconstriction: From Molecular Mechanisms to Medicine.
abstract: Hypoxic pulmonary vasoconstriction (HPV) is a homeostatic mechanism that is intrinsic to the pulmonary vasculature. Intrapulmonary arteries constrict in response to alveolar hypoxia, diverting blood to better-oxygenated lung segments, thereby optimizing ventilation/perfusion matching and systemic oxygen delivery. In response to alveolar hypoxia, a mitochondrial sensor dynamically changes reactive oxygen species and redox couples in pulmonary artery smooth muscle cells (PASMC). This inhibits potassium channels, depolarizes PASMC, activates voltage-gated calcium channels, and increases cytosolic calcium, causing vasoconstriction. Sustained hypoxia activates rho kinase, reinforcing vasoconstriction, and hypoxia-inducible factor (HIF)-1α, leading to adverse pulmonary vascular remodeling and pulmonary hypertension (PH). In the nonventilated fetal lung, HPV diverts blood to the systemic vasculature. After birth, HPV commonly occurs as a localized homeostatic response to focal pneumonia or atelectasis, which optimizes systemic Po2without altering pulmonary artery pressure (PAP). In single-lung anesthesia, HPV reduces blood flow to the nonventilated lung, thereby facilitating thoracic surgery. At altitude, global hypoxia causes diffuse HPV, increases PAP, and initiates PH. Exaggerated or heterogeneous HPV contributes to high-altitude pulmonary edema. Conversely, impaired HPV, whether due to disease (eg, COPD, sepsis) or vasodilator drugs, promotes systemic hypoxemia. Genetic and epigenetic abnormalities of this oxygen-sensing pathway can trigger normoxic activation of HIF-1α and can promote abnormal metabolism and cell proliferation. The resulting pseudohypoxic state underlies the Warburg metabolic shift and contributes to the neoplasia-like phenotype of PH. HPV and oxygen sensing are important in human health and disease.
authors.affiliation: Department of Medicine, Queen's University, Kingston, ON, Canada.
authors.forename: Kimberly J
authors.initials: KJ
authors.lastname: Dunham-Snary
authors.affiliation: Department of Medicine, Queen's University, Kingston, ON, Canada.
authors.forename: Danchen
authors.initials: D
authors.lastname: Wu
authors.affiliation: Department of Medicine, Queen's University, Kingston, ON, Canada.
authors.forename: Edward A
authors.initials: EA
authors.lastname: Sykes
authors.affiliation: Department of Medicine, Queen's University, Kingston, ON, Canada.
authors.forename: Amar
authors.initials: A
authors.lastname: Thakrar
authors.affiliation: Department of Medicine, Queen's University, Kingston, ON, Canada.
authors.forename: Leah R G
authors.initials: LRG
authors.lastname: Parlow
authors.affiliation: Department of Medicine, Queen's University, Kingston, ON, Canada.
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Mewburn
authors.affiliation: Department of Anesthesiology and Perioperative Medicine, Queen's University, Kingston, ON, Canada.
authors.forename: Joel L
authors.initials: JL
authors.lastname: Parlow
authors.affiliation: Department of Medicine, Queen's University, Kingston, ON, Canada. Electronic address: stephen.archer@queensu.ca.
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Archer
mesh_terms: D006801:Humans; D000860:Hypoxia / Q000378:metabolism / Q000503:physiopathology; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology*; D011652:Pulmonary Circulation / Q000502:physiology*; D011659:Pulmonary Gas Exchange / Q000502:physiology; D014661:Vasoconstriction / Q000502:physiology*
chemical_list: D051795:Hypoxia-Inducible Factor 1, alpha Subunit
keywords: chuvash polycythemia; high altitude pulmonary edema; mitochondria; oxygen-sensitive potassium channels; single-lung anesthesia; ventilation/perfusion matching