Co-existence of myosin heavy chain I and IIa isoforms in human skeletal muscle fibres with endurance training.
The myosin heavy chain (MHC) composition of single fibres from m. vastus lateralis was analysed by one-dimensional electrophoresis and immunoblotting in three groups of young men with distinct difference in physical activity patterns. No major co-existence of MHC isoforms was found in the group with some daily physical activity. In the very sedentary group, however, 19 +/- 5% (P less than 0.05) of the fibres exhibited coexistence of MHC type IIa and IIb. Further, in the endurance trained group co-existence of MHC type I and IIa was manifested in 36 +/- 4% (P less than 0.05) of the fibres. Disuse and extreme usage of muscle both give rise to an elevation in co-expression of MHC isoforms in single muscle fibres but of markedly different combination of isoforms.
August Krogh Institute, University of Copenhagen, Denmark.
H
H
Klitgaard
O
O
Bergman
R
R
Betto
G
G
Salviati
S
S
Schiaffino
T
T
Clausen
B
B
Saltin
D000328:Adult; D004586:Electrophoresis; D006801:Humans; D007150:Immunohistochemistry; D009132:Muscles / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D009218:Myosins / Q000032:analysis / Q000378:metabolism* / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology*
D009218:Myosins