Electrophoretic analysis of electrically trained skeletal muscle.
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.
O'Brien
G A
GA
Department of Cardiothoracic Surgery, National Heart and Lung Institute, London, England.
Corbett
J M
JM
Dunn
M J
MJ
Cumming
D V
DV
May
A J
AJ
Yacoub
M H
MH
D000818:Animals; D004558:Electric Stimulation; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods*; D009124:Muscle Proteins / Q000302:isolation & purification*; D009132:Muscles / Q000737:chemistry / Q000502:physiology*; D009218:Myosins / Q000302:isolation & purification; D010805:Physical Conditioning, Animal; D012756:Sheep; D014335:Tropomyosin / Q000302:isolation & purification; D014336:Troponin / Q000302:isolation & purification; D020107:Troponin T
D009124:Muscle Proteins; D014335:Tropomyosin; D014336:Troponin; D020107:Troponin T; D009218:Myosins