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Canine myocardial creatine kinase isoenzyme response to coronary artery occlusion
S W Sharkey1, K J Elsperger, M Murakami
1Cardiology Division, Hennepin County Medical Center, Minneapolis, Minnesota.
Abstract:
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.
Insights
Acute myocardial ischemia significantly alters the creatine kinase system in dogs. Both ischemic and non-ischemic heart tissue show changes in creatine kinase-MM and creatine kinase-MB activity after 3-hour occlusions.
Area of Science:
- Cardiology
- Biochemistry
- Physiology
Background:
- The response of the myocardial creatine kinase system to acute coronary artery occlusion is not well defined.
- Understanding these biochemical changes is crucial for diagnosing and managing myocardial ischemia.
Purpose of the Study:
- To investigate the serial changes in myocardial creatine kinase (CK) and its isoenzymes (CK-MM, CK-MB) following acute coronary artery occlusion in a canine model.
Main Methods:
- Open-chest dogs were subjected to occlusion of the left anterior descending (LAD) coronary artery.
- Myocardial tissue samples were collected from ischemic and non-ischemic regions at baseline and 1, 3, and 5 hours post-occlusion.
- Assays were performed for total CK, CK-MM, and CK-MB activities.
Main Results:
- Total CK activity decreased significantly in both ischemic and non-ischemic myocardium, primarily due to a decline in CK-MM.
- Concurrently, CK-MB activity significantly increased in both tissue types.
- These alterations were observed with occlusions of 3 hours or longer, but not with 1-hour occlusions.
Conclusions:
- Acute myocardial ischemia induces significant and rapid biochemical changes in the canine myocardial creatine kinase system.
- These changes occur both locally within the ischemic tissue and remotely in non-ischemic myocardial regions.
- The findings highlight the dynamic response of myocardial enzymes to ischemic events.