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Electrophoretic analysis of electrically trained skeletal muscle
G A O'Brien1, J M Corbett, M J Dunn
1Department of Cardiothoracic Surgery, National Heart and Lung Institute, London, England.
Electrophoresis
|September 1, 1992
Summary
Electrical stimulation transforms sheep muscle fibers to a slow type. Analysis reveals shifts in myosin, tropomyosin, and troponin T isoforms over five months, indicating complex thin filament adaptations.
Area of Science:
- Muscle physiology
- Molecular biology
- Protein biochemistry
Background:
- Skeletal muscle exhibits plasticity in response to training stimuli.
- Fiber-type transformation is a key adaptation to altered muscle activity.
- Understanding molecular changes in contractile proteins is crucial for muscle adaptation research.
Purpose of the Study:
- To investigate the time course of contractile protein isoform expression changes during electrical stimulation-induced fast-to-slow muscle fiber transformation in sheep.
- To analyze alterations at both protein and mRNA levels for key contractile proteins.
Main Methods:
- Electrical stimulation of sheep latissimus dorsi muscle.
- One- and two-dimensional gel electrophoresis for protein analysis.
- Computer analysis for quantitative isoform expression.
- Time-course analysis over 5 months.
Main Results:
- Myosin heavy chain and regulatory myosin light chain predominantly shifted to slow isoforms (86% and 92%) by 3 months.
- Slow tropomyosin alpha-subunit isoforms reached 64% of total alpha expression by 3 months.
- Troponin T isoform switching was slower, with slow isoforms predominating over fast ones after 5 months, revealing heterogeneity.
Conclusions:
- Electrical training induces significant fast-to-slow fiber-type transformation in sheep skeletal muscle.
- Adaptation involves differential regulation of myosin, tropomyosin, and troponin T isoforms.
- Skeletal muscle thin filaments can exhibit diverse combinations of fast and slow isoforms during adaptation.