Sarcolemmal enzymes and Na+ -Ca2+ exchange in hypoxic, ischemic, and reperfused rat hearts.
Isolated spontaneously beating rat hearts were perfused in the Langendorff mode and divided into four groups, i.e., control (aerobic), hypoxic (95% N2-5% CO2), ischemic, and ischemic reperfused. After a total of 90 min of perfusion, the sarcolemma was isolated and enzymatically characterized. Ouabain-sensitive Na+-K+-ATPase was inhibited in all three experimental groups, whereas K+-stimulated phosphatase activity was decreased only in the ischemic and reperfused groups compared with control. 5'-Nucleotidase activity was inhibited (P less than 0.05) only in the ischemic group. Mg2+-ATPase activity was not different from control. Passive Ca2+ uptake and Ca2+ efflux were not significantly altered by any of the interventions. Na+-Ca2+ exchange rate, but not capacity, was decreased (by 32-42%) in the ischemic group but this was partially reversed on reperfusion. These results suggest that changes secondary to lack of flow rather than O2 play a major role in the etiology of ischemic damage to the membrane and that a 15-min period of reperfusion after 60 min of ischemia does not exacerbate this damage.
D015720:5'-Nucleotidase; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase; D002118:Calcium / Q000378:metabolism*; D003327:Coronary Disease / Q000378:metabolism*; D000860:Hypoxia / Q000378:metabolism*; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D009708:Nucleotidases / Q000378:metabolism; D010477:Perfusion; D051381:Rats; D011919:Rats, Inbred Strains; D012508:Sarcolemma / Q000201:enzymology*; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D013385:Succinate Dehydrogenase / Q000378:metabolism
D012964:Sodium; D013385:Succinate Dehydrogenase; D009708:Nucleotidases; D015720:5'-Nucleotidase; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium