title: Restoration of hypoxic pulmonary vasoconstriction following normoxia in isolated dog lungs occurs in the presence but not in the absence of prostaglandin synthesis inhibitors.
abstract: We examined the possibility that eucapnic (6% CO2) alveolar hypoxia (3% O2) in isolated dog lungs not only produces an increase in pulmonary vascular resistance but also initiates the subsequent prostaglandin (PG) dependent reduction in this hypoxic pulmonary vasoconstriction (HPV). We determined that a reduction in HPV occurred after 45 min including a 35-min period of hypoxia (prolonged hypoxia), after 45 min of intermittent hypoxia, and after 45 min of normoxia (14% O2). These reductions were PG dependent, since they were reversed or prevented by PG synthesis inhibitors in the autologous blood perfusate. In addition to the PG-dependent reduction that required 45 min to develop, a separate reduction in HPV also occurred. This reduction occurred during prolonged hypoxia, was not prevented by PG synthesis inhibitors, was reversed after 6 min of normoxia, and was reproduced in a second period of prolonged hypoxia. We conclude that alveolar hypoxia did not initiate the PG-dependent reduction in HPV, since it occurred after normoxia as well as after hypoxia. However, hypoxia appeared to contribute to a separate PG-independent reduction in HPV, since this reduction was initiated and maintained exclusively during prolonged hypoxia and was unaffected by PG synthesis inhibitors.
mesh_terms: D000818:Animals; D004285:Dogs; D000860:Hypoxia / Q000503:physiopathology*; D008168:Lung / Q000187:drug effects*; D011448:Prostaglandin Antagonists / Q000494:pharmacology*; D011652:Pulmonary Circulation; D012016:Reference Values; D013997:Time Factors; D014661:Vasoconstriction / Q000187:drug effects*; D014666:Vasomotor System / Q000503:physiopathology
chemical_list: D011448:Prostaglandin Antagonists