title: Sodium pump failure in hypoxia and reoxygenation.
abstract: Sodium pump measurements have not been previously documented in the intact heart close to the onset of irreversible injury in hypoxia and reoxygenation. In the present experiments, Rb+ uptake was measured in the presence and absence of ouabain in Langendorff-perfused rat hearts. In the presence of ouabain, Rb+ uptake was increased after 10 min hypoxia (P < 0.05 vs. controls), but not after 30 min hypoxia, suggesting transient activation of a passive pathway such as the ATP-sensitive K+ channels. Passive Rb+ uptake was normal during post-hypoxic reoxygenation. Active Rb+ uptake was reduced after 30 min hypoxia, increased on reoxygenation after 10 min hypoxia, and failed to recover on reoxygenation after 30 min hypoxia (P < 0.001, P < 0.05 and P < 0.001, respectively, vs. controls). Sodium pump failure may lead to calcium overload through sodium-calcium exchange, and may be a decisive influence in post-hypoxic reoxygenation injury.
authors.affiliation: Department of Physiology, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: P M
authors.initials: PM
authors.lastname: Grinwald
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D006321:Heart / Q000187:drug effects*; D000860:Hypoxia / Q000188:drug therapy* / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000378:metabolism; D010042:Ouabain / Q000494:pharmacology*; D010100:Oxygen / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012413:Rubidium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000502:physiology*
chemical_list: D010042:Ouabain; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium; D010100:Oxygen; D002118:Calcium