HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Owen, V J Articles by Stephenson, D G Search for Related Content PubMed PubMed Citation Articles by Owen, V J Articles by Stephenson, D G

School of Zoology, La Trobe University, Bundoora, Victoria, Australia.

1. The effect of low [ATP] on depolarization-induced Ca2+ release from the sarcoplasmic reticulum (SR) was examined using mechanically skinned skeletal muscle fibres of the toad. The amount of Ca2+ released was determined by examining the extent of SR Ca2+ depletion following a single depolarization in the presence of specified total [ATP] and free [Mg2+] and 1 mM EGTA (< 10 nM Ca2+). 2. Reducing the total [ATP] from 8 to 2 mM did not significantly affect the extent of depolarization-induced Ca2+ release. When the total [ATP] was lowered to 0.5 mM, depolarization-induced Ca2+ release was markedly reduced. The additional presence of 1.5 mM AMP did not reverse this effect of low [ATP]. 3. At each total [ATP], elevation of the free [Mg2+] from the normal resting level of 1 mM to 3 mM, caused a similar reduction in depolarization-induced Ca2+ release. This effect was not due to the concomitant decrease in free [ATP] and occurred independently of the reduction in Ca2+ release observed at very low total [ATP]. 4. These results show myoplasmic [ATP] modulates depolarization-induced Ca2+ release. Thus, if the total [ATP] near the Ca2+ release channels becomes locally depleted in severely fatigued muscle fibres, it may contribute, in combination with an accompanying increase in free [Mg2+], to the reported reduction in Ca2+ release.

This article has been cited by other articles:

				D. G. Allen, G. D. Lamb, and H. Westerblad Skeletal Muscle Fatigue: Cellular Mechanisms Physiol Rev, January 1, 2008; 88(1): 287 - 332. [Abstract] [Full Text] [PDF]

				T. L Dutka and G. D Lamb Effect of low cytoplasmic [ATP] on excitation-contraction coupling in fast-twitch muscle fibres of the rat J. Physiol., October 15, 2004; 560(2): 451 - 468. [Abstract] [Full Text] [PDF]