Characteristics of myosin isoforms in mammalian skeletal muscle

The distribution of myosin heavy (MyHC) and myosin light chain (MyLC) isoform pattern in horse, rat and human skeletal muscle was investigated to establish relations between them and the role of myosin isoform patterns in mammalian muscle with different twitch characteristics was studied. These two isoforms were separated in a SDS-PAGE gel system, stained using the coomassie and silver staining procedures, and the results were analyzed using a G:BOX system. The relative content of MyHC I isoform in muscle was 2.6 times higher than in human compared to horse muscle (p < 0.001), and 6.3 times higher than in rat muscle (p < 0.001). The relative content of MyHC IIx/d isoform in horse muscle is 2.7 times, and in rat muscle 2.2 times higher in comparison with human muscle (p < 0.001). The role of the MyLC isoform distribution in mammalian skeletal muscle seems to depend on the oxidative capacity of muscles.