Creatine kinase isoenzymes in serum of pigs having myocardial and skeletal muscle necrosis.

Serum creatine kinase (CK) and lactic dehydrogenase (LD) isoenzyme activities were measured in blood serum of pigs having myocardial damage and skeletal muscular lesions. Myocardial and muscular damage was induced by restraint stress provoked by intravenous infusion of a pharmacological restraint (succinylcholine-chloride) during 12 minutes. Pigs of Swedish Landrace and Swedish Landrace X Yorkshire breed, stress-susceptible (halothane-sensitive) and nonreacting pigs were studied. Severe myocardial damage and slight to moderate skeletal muscle necrosis were found 24 hours after restraint stress in the stress-susceptible pigs whereas in nonreacting pigs generally only myocardial lesions of moderate extent were registered. No significant increase was detected in the serum CK-BB (CK-1) or CK-MB (CK-2) activity whereas a pronounced elevation of the CK-MM (CK-3) activity was found, particularly in the stress-sensitive animals. In the myocardial tissue of pigs only a low CK-MD activity was found (about 4-5% CK-MD in addition to CK-MM) and this may explain the low CK-MB activity in serum of pigs subjected to severe myocardial damage. This is further supported by the pronounced increase in the anodal serum fractions LD 1-2 in animals free from skeletal muscular lesions. In the halothane-sensitive pigs skeletal muscle necrosis besides the myocardial lesions contributed to the high levels of CK-MM activity in serum.