AJP - Cell Physiology, Vol 261, Issue 1 C169-C176, Copyright © 1991 by American Physiological Society
Reduced glycolytic metabolism in regenerated fast-twitch skeletal muscle
M. A. Wineinger, F. Gorin, R. Tait, B. Froman and R. C. Carlsen
Department of Human Physiology, School of Medicine, University of California, Davis 95616.
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.
