In vivoevaluation of intracellular pH and high‐energy phosphate metabolities during regional myocardial ischemia in cats using31P nuclear magnetic resonance

Abstract

Phosphorus-31 nuclear magnetic resonance spectroscopy (³¹P NMR) was used to asses the temporal changes of high-energy phosphate metabolites in the region of acute myocardial ischemia of open-chest cats. Eight anesthetized cats were studied following ligation of the left anterior descending coronary artery. Creatine phosphate showed a 79 ± 16% (mean ± SD) reduction by 4 min after the onset of ischemia. Prominent qualitative reductions of the spectral peak of creatine phosphate occurred by 40 s after ischemia. Adenosine triphosphate measured under the beta spectral peak (β-ATP) decreased 37 ± 9% by 20–25 min after ligation of the left anterior descending coronary artery. These reductions developed more slowly and were of smaller magnitude than those of creatine phosphate. Intracellular pH decreased from 7.39 ± 0.07 to 7.13 ± 0.09 units by 40 s after ischemia. By 30 min, pH decreased to 6.07 ± 0.40 units. The study shows, therefore, the temporal changes of high-energy phosphate metabolites during ischemia in localized regions of the myocardium of open-chest animals. © 1986 Academic Press, Inc.