Decay of Ca2+ and force transients in fast- and slow-twitch skeletal muscles from the rat, mouse and Etruscan shrew.
Isometric single-twitch force and intracellular Ca2+ transients were recorded simultaneously, using fura-2, from slow- and fast-twitch muscle fibres of the rat, mouse and Etruscan shrew Suncus etruscus. In the slow-twitch rat soleus, force half-relaxation time was three times longer than the 50% decay time of the fura-2 signal. In contrast, in the fast-twitch extensor digitorum longus muscles of all three animals, muscle relaxation preceded Ca2+ decay. It is proposed that this surprising property of fast-twitch muscles is due to their pCa-tension curve, which is shifted to the right compared with that of slow-twitch muscle.
Wetzel
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Zentrum Physiologie, Medizinische Hochschule Hannover, Germany.
Gros
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G
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D005456:Fluorescent Dyes; D016257:Fura-2; D066298:In Vitro Techniques; D007424:Intracellular Fluid / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D009119:Muscle Contraction / Q000502:physiology*; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism / Q000502:physiology; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism / Q000502:physiology; D009126:Muscle Relaxation / Q000502:physiology; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012788:Shrews; D013045:Species Specificity
D005456:Fluorescent Dyes; D002118:Calcium; D016257:Fura-2