Mitochondrial and MB isoenzymes of creatinine kinase in cerebrospinal fluid from patients with hypoxic-ischemic brain damage

Measurements of cerebrospinal fluid (CSF) creatinine kinase (CK, EC 2.7.3.2) isoenzyme activity have been used to predict outcome in patients with acute brain injury following cardiac arrest. We identified two CK isoenzymes previously unreported in CSF from 16 patients with hypoxic-ischemic brain damage. Prior to analysis, the CK in the CSF samples was reactivated with dithiothreitol. CK isoenzymes were identified using electrophoretic and immunologic methods. Total CK activity ranged from 23 to 924 U/L (mean 452). CSF-CK-BB was the predominant isoenzyme present in all cases. In addition to CSF-CK-BB, the authors identified CSF-CK-MM in 6 cases, CSF-CK-MB in 8 cases, and CSF-mitochondrial-CK in 14 cases. The presence of CSF-CK-MM was significantly related to blood contaminating the CSF (P < 0.02). It is proposed that CSF-CK-MB results from recombination of CK-MM and CK-BB in CSF and that mitochondrial CK is released with CK-BB into the CSF from the damaged brain tissue.