Reduced glycolytic metabolism in regenerated fast-twitch skeletal muscle.
Freely grafted rat extensor digitorum longus (EDL) muscles were subjected to low-frequency stimulation in an anaerobic environment to determine whether regenerating fast-twitch muscles regain normal glycolytic metabolic capacity. Regenerating muscles were tested at 28, 42, and 76 days after the graft procedure. Stabilized grafts (76 days) produced approximately 60% of the lactate generated by intact, control EDL subjected to the same stimulus paradigm and developed half the estimated increase in H+. The grafts exhibited the same relative decline in force after 5 min of anaerobic stimulation as control EDL but maintained relatively constant levels of ATP while consuming phosphocreatine. This study indicates that regenerating fast-twitch skeletal muscle has a reduced ability to initiate glycolytic activity during exercise. The data also indicate that a small population of regenerating fast-twitch fibers express the slow isoform of myosin heavy chain (beta-MHC) with maximum expression occurring at 56 days postsurgery.
Wineinger
M A
MA
Department of Human Physiology, School of Medicine, University of California, Davis 95616.
Gorin
F
F
Tait
R
R
Froman
B
B
Carlsen
R C
RC
D000222:Adaptation, Physiological; D000255:Adenosine Triphosphate / Q000378:metabolism; D000693:Anaerobiosis; D000818:Animals; D001483:Base Sequence; D001835:Body Weight; D004247:DNA; D015342:DNA Probes; D005260:Female; D006019:Glycolysis; D006863:Hydrogen-Ion Concentration; D007773:Lactates / Q000378:metabolism; D008969:Molecular Sequence Data; D009119:Muscle Contraction; D009132:Muscles / Q000378:metabolism* / Q000502:physiology / Q000637:transplantation; D009218:Myosins / Q000378:metabolism; D010725:Phosphocreatine / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012038:Regeneration
D015342:DNA Probes; D007773:Lactates; D010725:Phosphocreatine; D000255:Adenosine Triphosphate; D004247:DNA; D009218:Myosins