Release of alpha-actin into serum after skeletal muscle damage.

OBJECTIVE: The skeletal muscle protein alpha-actin was investigated in the serum of subjects with severe skeletal muscle damage to assess its utility as a reliable and predictive marker of muscle damage. METHODS: Serum samples were obtained from 33 healthy controls and 33 patients with severe skeletal muscle damage, defined by a total creatine kinase value of >500 IU/l (Rosalki method). Troponin I, troponin T, and myoglobin concentrations were determined by immunoassay and alpha-actin concentrations by Western blot and densitometry. RESULTS: The mean serum concentration of alpha-actin in controls and patients with skeletal muscle damage was 600.9 and 1968.51 ng/ml, respectively, a statistically significant difference. Sera of patients with muscle damage showed higher levels of alpha-actin than of troponin or myoglobin. No significant difference in troponin I levels was observed between the groups. CONCLUSIONS: According to these results, alpha-actin was the most significant skeletal muscle damage marker analysed and may be an ideal candidate for the identification of all types of myofibre injury, including sports injuries. Our findings support the use of alpha-actin as a marker alongside other currently used biological proteins.