Divalent cation-activated ATP hydrolysis by mitochondrial ATP'ase--mechanism for energy depletion in ischemic reperfused myocardium.
Recovery of high-energy compounds by ischemic myocardium is believed to be important for its return to normal functioning. While it has been previously shown that oxidative phosphorylation is markedly reduced in mitochondria isolated from ischemic myocardium in the presence of all substrates, alterations in ATPase activity have not been confirmed. This study demonstrates that, although the rate of ATP hydrolysis produced by mitochondria isolated from 2-hr ischemic myocardium does not significantly differ from that produced by non-ischemic mitochondria, the rate produced by 2-hr ischemic, 2 hr reperfused mitochondria is significantly higher. Also, Ca++ content was observed to be higher in reperfused than in non-reperfused ischemic mitochondria. The addition of EDTA, EGTA, or oligomycin to the reperfused ischemic mitochondria resulted in the inhibition of ATPase activity. These results indicate that mitochondrial ATPase in ischemic myocardium is activated by Ca++ ions and that ischemic reperfused myocardium may contain mitochondria with uncontrolled ATPase activity such that high energy phosphate supplies are excessively depleted when the cells are reperfused.
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D003327:Coronary Disease / Q000201:enzymology*; D004492:Edetic Acid / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D006868:Hydrolysis; D008929:Mitochondria, Heart / Q000201:enzymology*; D010085:Oxidative Phosphorylation; D010477:Perfusion; D013552:Swine; D013890:Thiourea / Q000378:metabolism; D013997:Time Factors
D004533:Egtazic Acid; D004492:Edetic Acid; D000251:Adenosine Triphosphatases; D013890:Thiourea