Sodium pump failure in hypoxia and reoxygenation.
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.
Grinwald
P M
PM
Department of Physiology, University of Melbourne, Parkville, Victoria, Australia.
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*
D010042:Ouabain; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium; D010100:Oxygen; D002118:Calcium