Levels of Myosin Heavy Chain Fragments in Myoskeletal Injuries

Abstract

Myosin heavy chain (MHC) is a structurally bound contractile protein of the thick filaments. The magnitude of myoskeletal injury may be estimated by serial determinations of these contractile proteins released into the circulation as a consequence of loss of cell membrane integrity. The polymorphism of MHC is believed to be responsible, at least in part, for the variable contraction velocity of muscles. It was the aim of the present study to confirm the utility of MHC for the assessment of skeletal muscle damage within 24 hr of injury in patients with myoskeletal injuries. Plasma MHC fragments was measured in 25 patients with muscle injuries. Samples were obtained immediately on hospital admission (A1) and 24 hr after admission (A2). These were compared with 15 noninjured controls. In addition, creatine kinase (CK), myoglobin and cardiac troponin I (cTnI) were measured in order to confirm the extent of the injury and to exclude protein released from the heart. Radioimmunoassay, enzyme immunoassay, and one-step immunoenzymometric assay (IEMA) techniques were used for measurements of plasma MHC fragments, CK plus myoglobin and cTnI, respectively. Mean (SD) uU/l of MHC was (94.1±116.1) p=NS and (673.3±1943) p<0.0001 on A1 and A2, respectively, compared to controls (96.8±96.35). CK (IU/l) was 226.0±231.0 on A1 and 451.0±678.0 on A2 compared to 104.0±51.0 on controls. Myoglobin was 200% higher at A1 and A2 than at controls. We substantiate previous study and conclude that MHC could be a useful tool in the study of myoskeletal injuries in human.