Absence of a lateral border zone of intermediate creatine phosphokinase depletion surrounding a central infarct 24 hours after acute coronary occlusion in the dog.

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Abstract
Myocardial creatine phosphokinase (CPK) activity was measured as an indicator of cell viability 24 hours after ligation of the left anterior sescending coronary artery (LAD) in normal myocardium, the entire region supplied by the LAD, and individual samples from the border and center of the infarct. Tissue supplied by the LAD and delineated by dye was carefully dissected from normal tissue along the stained border, CPK activity in the ischemic myocardium was calculated by assuming normal CPK activity in the ischemic myocardium was calculated by assuming normal CPK activity in normal myocardium interdigitating with ischemic tissue at the border. Normal tissue was marked prior to occlusion with microspheres injected into the left atrium, whereas the distal portion of the LAD was perfused separately with unlabeled blood from a reservoir. With this correction, the CPK activity in the ischemic tissue from the lateral border of the infarct was essentially the same as in samples from the center, whereas that in the normal tissue immediately adjacent to the stained border was equal to values in remote normal myocardium. Thus, CPK depletion throughout the entire ischemic myocardium was nearly equal to CPK depletion in the center of the infarct. The uncorrected intermediate CPK levels in the individual samples from the border of the stained region correlated with the amount of normal tissue contaminating these samples. However, differences in CPK depletion across the heart wall resulted in the most depletion in the subendocardium and the least in the epicardium. Further more, coronary collateral blood flow measured 10 minutes after occlusion correlated well with the subsequent extent of CPK depletion.