Canine myocardial creatine kinase isoenzyme response to coronary artery occlusion.

The response of the myocardial creatine kinase system to acute coronary artery occlusion is not well defined. In the present study, we measured serial changes in myocardial creatine kinase and creatine kinase-MB activities after acute occlusion of the left anterior descending (LAD) coronary artery in 20 open-chest pentobarbital-anesthetized dogs. Tissue samples were obtained from both ischemic and nonischemic left ventricular myocardium at base line and 1-, 3-, and 5-h intervals after LAD occlusion and assayed for total creatine kinase and the isoenzymes creatine kinase-MM, and creatine kinase-MB. Total creatine kinase activity declined significantly in both the ischemic and the nonischemic tissue because of a decline in creatine kinase-MM activity. Concomitantly, creatine kinase-MB activity increased significantly in both the ischemic and the nonischemic tissue. These changes were observed when the duration of the LAD occlusion was 3 h or longer, but not when the duration of the occlusion was 1 h. Thus acute myocardial ischemia causes pronounced changes in the canine myocardial creatine kinase system. These rapid biochemical alterations occur both locally in ischemic tissue and remotely in nonischemic tissue.