Electrophoretic analysis of electrically trained skeletal muscle

Abstract

Sheep latissimus dorsi muscle was electrically trained, thereby inducing fast-to-slow fibre-type transformation. Using a combination of one- and two-dimensional gel electrophoresis techniques with computer analysis, we have analysed altered expression of contractile protein isoforms at protein and mRNA level over a time course of electrical training extending to 5 months. Myosin heavy chain and regulatory myosin light chain analysis showed predominant expression of their slow isoforms (86% and 92%, respectively) after 3 months of training. At the same time point, however, tropomyosin analysis revealed that the slow isoform of the alpha-subunit accounted for 64% of the total alpha expression. Troponin T isoform switching proceeded more slowly over the same time course than tropomyosin and the thick filament proteins studied. Troponin T analysis revealed 5 fast and 2 slow isoforms in the sheep, of which the second slow isoform only became clearly visible after 5 months' training. At this time point the two slow isoforms were more predominant than their fast counterparts. This suggests that a wide heterogeneity of fast and slow isoform combinations are possible in the thin filament of skeletal muscle.

Adaptive change in electrically stimulated muscle: A framework for the design of clinical protocols

“…The fast–slow transformation has been studied in most detail in the rabbit, but it has also been described in rat,83–85 cat,6, 70, 86 dog,87–91 goat,92, 93 sheep,94–96 pig,97 and man 98, 99. A comparison of the results from these different species reveals an interesting fact: less intensive stimulation is needed to produce adaptive changes in those of larger body size 100, 101.…”

The adaptive response of skeletal muscle: What is the evidence?

“…Buller and his colleagues conducted their experiments in cats, whereas the effects of stimulation had been demonstrated in rabbits. However, in the subsequent 4 decades, the results have been reproduced in rat, [14][15][16] cat, 8,17,18 dog, [19][20][21][22][23] goat, 24,25 sheep, [26][27][28] pig, 29 and man. 30,31 These species differ only in their sensitivity to increased activity.…”