Abstract
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.
Highlights
Myosin controls the functional properties of skeletal muscle fibers
This study investigated the distribution of MyHC and myosin light chain (MyLC) isoforms pattern in horse, rat, and human skeletal muscle to clarify the role of myosin isoforms in skeletal muscles of small and large mammalian and human muscle as well as in muscle with differences in twitch characteristics
The comparison of MyHC and MyLC isoforms pattern in human quadriceps femoris muscle, Akhal-Teke horse Gluteus medius muscle, and Wistar rat Pla muscle show that MyHC I isoform relative content in human muscle is 2.6 times higher than in horse muscle and 6.3 times higher than in rat muscle
Summary
Myosin controls the functional properties of skeletal muscle fibers. Nearly fifty years ago, Barany showed that maximal shortening velocity within skeletal muscle of various mammals was related to actomyosin ATPase activity [1], and the major component of myosin molecule the MyHC isoform was responsible for this [2,3]. MyHC fastest isoform IIb isoform has been shown to be species-specific [17] and muscles IIb isoform has only been shown to be expressed in rodents [18], marsupials [19] and as an exception among large animals in the pig hybrid IIx/b fibers [20]. As external factors, such as functional activity or inactivity, may influence myosin isoform composition [21,22], we used sedentary humans, horses, and rats
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