Simultaneous cardiac mechanics and phosphorus-31 NMR spectroscopy during global myocardial ischemia and reperfusion in the intact dog.
To investigate the high-energy phosphate metabolic correlates of left ventricular (LV) dysfunction during the onset and recovery from severe, global myocardial ischemia in vivo, seven preinstrumented closed-chest dogs had ECG-gated phosphorus-31 (31P) NMR-spectroscopy (NMR-S) studies performed and LV micromanometer and sonomicrometer data measured before, during, and every 5 min following severe occlusive global myocardial ischemia. Ischemic LV + dP/dtmax fell from 2396 +/- 576 mm Hg/s at baseline to 2185 +/- 478 mm Hg/s (p less than 0.05) and did not normalize until after 30 min of reperfusion. LV ejection fraction (EF) decreased significantly (0.32 +/- 0.07 EF units to 0.12 +/- 0.13 EF units; p less than 0.05) and did not recover by 30 min of reperfusion (0.27 +/- 0.09 units; P less than 0.05 vs baseline). Simultaneous 31P NMR-S studies demonstrated excellent beta-ATP signal-to-noise (10 +/- 4:1). Myocardial acidosis occurred during global ischemia (delta pH = -0.22 +/- 0.23 units; p less than 0.05), with recovery at 30 min of reperfusion. Inorganic phosphate/phosphocreatine ratio (Pi/PCr) increased significantly during ischemia (0.46 +/- 0.07 to 0.61 +/- 0.07; P less than 0.05), with delayed normalization of this ratio at 30 min of reperfusion. beta-ATP peak area did not change during ischemia. Pi/PCr and LV contractility (+dP/dtmax) were significantly correlated at baseline (r = -0.70) and during global ischemia (r = -0.78; p less than 0.01), but not during recovery (r = 0.006; p = NS). Therefore, the simultaneous evaluation of high-fidelity hemodynamic data and topical 31P NMR-S can be performed in the intact state.
Miller
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Department of Medicine (Cardiology), University of Texas Health Science Center, San Antonio 78284.
Salinas
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Walsh
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D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001794:Blood Pressure; D003326:Coronary Circulation; D003327:Coronary Disease / Q000378:metabolism* / Q000503:physiopathology; D004285:Dogs; D006321:Heart / Q000503:physiopathology*; D009682:Magnetic Resonance Spectroscopy; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption; D010725:Phosphocreatine / Q000378:metabolism; D010758:Phosphorus; D013318:Stroke Volume; D016277:Ventricular Function, Left
D010725:Phosphocreatine; D010758:Phosphorus; D000255:Adenosine Triphosphate