Creatine Kinase and Neuron-Specific Enolase

Abstract

Creatine kinase (CK) isoenzymes, brain specific (CK-BB) and cardiac muscle specific (CK-MB), have been used as serum markers for brain and cardiac injury. CK-BB is found in high concentrations in the brain where it is produced by astrocytes. Previous radioimmunoassay procedures for CK-BB and CK-MB involved polyclonal antisera that recognised the B subunit with a resultant degree of cross-reaction between the two species. In this study, CK-BB and -MB isoenzymes were detected using enzyme-linked immunoabsorbent assay techniques employing monoclonal antibodies. No detectable cross-reactivity occurred in the measuring range 0–1,000 μg/l and the detection limit was 0.01 μg/l. Neuron-specific enolase (γγ-enolase; NSE) is a specific isoenzyme of the glycolytic enzyme enolase, which is characterised by its consistent occurrence in the cytoplasm of mature neurons. It was detected using a double antibody radioimmunoassay with measuring range and detection limit of 2.0–200 μg/l and 2.0 μg/l, respectively. Blood samples were obtained with informed consent from adult amateur oarsmen before and after a rowing ergometer test and from adult amateur boxers before and after a bout. No significant changes were found between the pre- and postexercise serum levels of CK-BB, CK-MB, or NSE in the oarsmen, providing no evidence of neuronal damage, even at maximal exercise. Both CK-MB levels unchanged. These serum markers indicate damage to both astrocytes and mature neurons with leakage of these intracellular enzymes into the circulation and identify boxing as a cause of acute brain injury.