Role of glycogen availability in sarcoplasmic reticulum Ca2+ kinetics in human skeletal muscle.
Glucose is stored as glycogen in skeletal muscle. The importance of glycogen as a fuel during exercise has been recognized since the 1960s; however, little is known about the precise mechanism that relates skeletal muscle glycogen to muscle fatigue. We show that low muscle glycogen is associated with an impairment of muscle ability to release Ca(2+), which is an important signal in the muscle activation. Thus, depletion of glycogen during prolonged, exhausting exercise may contribute to muscle fatigue by causing decreased Ca(2+) release inside the muscle. These data provide indications of a signal that links energy utilization, i.e. muscle contraction, with the energy content in the muscle, thereby inhibiting a detrimental depletion of the muscle energy store.
Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense M, Denmark. nortenblad@health.sdu.dk
Niels
N
Ørtenblad
Joachim
J
Nielsen
Bengt
B
Saltin
Hans-Christer
HC
Holmberg
D000328:Adult; D056352:Athletes; D001707:Biopsy, Needle; D002118:Calcium / Q000378:metabolism*; D003408:Cresols / Q000494:pharmacology; D004040:Dietary Carbohydrates / Q000378:metabolism / Q000494:pharmacology; D006003:Glycogen / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D019344:Lactic Acid / Q000097:blood; D008297:Male; D046529:Microscopy, Electron, Transmission; D018763:Muscle Fatigue / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D009210:Myofibrils / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D018995:Myosin Heavy Chains / Q000378:metabolism; D052097:Quadriceps Muscle / Q000187:drug effects / Q000502:physiology; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D012865:Skiing / Q000502:physiology; D055815:Young Adult
D003408:Cresols; D004040:Dietary Carbohydrates; D019344:Lactic Acid; C006984:chlorocresol; D006003:Glycogen; D018995:Myosin Heavy Chains; D002118:Calcium