Functional significance of Ca2+ in long-lasting fatigue of skeletal muscle.
Repeated activation of skeletal muscle causes fatigue, which involves a reduced ability to produce force and slowed contraction regarding both the speed of shortening and relaxation. One important component in skeletal muscle fatigue is a reduced sarcoplasmic reticulum (SR) Ca2+ release. In the present review we will describe different types of fatigue-induced inhibition of SR Ca2+ release. We will focus on a type of long-lasting failure of SR Ca2+ release which is called low-frequency fatigue, because this type of fatigue may be involved in the muscle dysfunction and chronic pain experienced by computer workers. Paradoxically it appears that the Ca2+ released from the SR, which is required for contraction, may actually be responsible for the failure of SR Ca2+ release during low-frequency fatigue. We will also discuss the relationship between gross morphological changes in muscle fibres and long-lasting failure of SR Ca2+ release. Finally, a model linking muscle cell dysfunction and muscle pain is proposed.
Westerblad
H
H
Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden. hakan.westerblad@fyfa.ki.se
Bruton
J D
JD
Allen
D G
DG
Lännergren
J
J
D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D020013:Calcium Signaling / Q000502:physiology*; D006801:Humans; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism
D002118:Calcium