Skeletal muscle CK-B activity in neurogenic muscular atrophies.

Creatine kinase isoenzymes were determined in skeletal muscle biopsy specimens of 34 patients suffering from neurogenic muscular atrophies. The findings were compared: (1) with those of 38 control muscle samples and (2) with those in 41 muscular dystrophies and other myopathic conditions. The measurements were made by electrophoretic separation and elution of the isoenzymes and by immunoinhibition assay. The results showed that the total and specific CK activity were significantly decreased (P less than 0.005) in neurogenic atrophies in contrast to myopathic conditions where no differences from control levels were observed. This decrease was due to a decrease of the CK-M subunit activity, while the CK-B subunit was elevated. The muscle CK-MB activity was considerably elevated in muscular dystrophies (P less than 0.02) and myositis (P less than 0.001), but it was also slightly elevated in neurogenic conditions. The similarity of the muscle CK isoenzyme pattern in neurogenic atrophies and myotonic dystrophy was noted. These findings could possibly reflect considerable difference in the regeneration process of neurogenic atrophies and muscular dystrophies.