Regional creatine kinase, adenylate kinase, and lactate dehydrogenase in normal canine brain

Following acute stroke, creatine kinase and other enzymes are released into the cerebrospinal fluid and blood from injured brain tissue. To determine whether regional differences in brain enzyme activity might exist and therefore affect the amount of enzyme released, we quantified the levels of creatine kinase, adenylate kinase, and lactate dehydrogenase in 12 regions of normal canine brain (n = 4). Adenylate kinase activity varied the least among regions (49 ± 7 units/g), followed by lactate dehydrogenase activity (122 ± 28 units/g). The pattern for both adenylate kinase and lactate dehydrogenase was higher activity in predominantly gray matter areas, lower activity in white matter, and intermediate activity in mixed regions. The distribution of creatine kinase brain isoenzyme and mitochondrial creatine kinase in canine brain was less predictable, showed wider variations among regions (isoenzyme, 462 ± 116 units/g; mitochondrial, 42 ± 20 units/g). Even cerebral gray matter demonstrated substantial regional variations in creatine kinase brain isoenzyme, ranging from 606 units/g in the parietal cortex to 329 units/g in the temporal cortex. We conclude that the content of creatine kinase brain isoenzyme varies more than twofold among areas of brain. This regional variation may be important in the interpretation of creatine kinase brain isoenzyme measurements in cerebrospinal fluid and serum used to assess neurologic injury following stroke.