| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Department of Medicine, University of California, San Diego, La Jolla, California 92093-0623
We tested the hypothesis that the mechanisms involved in the more rapid onset of fatigue when O2 availability is reduced in contracting skeletal muscle are similar to those when O2 availability is more sufficient. Two series of experiments were performed in isolated, single skeletal muscle fibers from Xenopus laevis. First, relative force and free cytosolic Ca2+ concentrations ([Ca2+]c) were measured simultaneously in single fibers (n = 6) stimulated at increasing frequencies (0.25, 0.33, 0.5, and 1 Hz) at an extracellular PO2 of either 22 or 159 Torr. Muscle fatigue (force = 50% of initial peak tension) occurred significantly sooner (P < 0.05) during the low- (237 ± 40 s) vs. high-PO2 treatments (280 ± 38 s). Relative [Ca2+]c was significantly decreased from maximal values at the fatigue time point during both the high- (72 ± 4%) and low-PO2 conditions (78 ± 4%), but no significant difference was observed between the treatments. In the second series of experiments, using the same stimulation regime as the first, fibers (n = 6) exposed to 5 mM caffeine immediately after fatigue demonstrated an immediate but incomplete relative force recovery during both the low- (89 ± 4%) and high-PO2 treatments (82 ± 3%), with no significant difference between treatments. Additionally, there was no significant difference in relative [Ca2+]c between the high- (100 ± 12% of prefatigue values) and low-PO2 treatments (108 ± 12%) on application of caffeine. These results suggest that in isolated, single skeletal muscle fibers, the earlier onset of fatigue that occurred during the low-extracellular PO2 condition was modulated through similar pathways as the fatigue process during the high and involved a decrease in relative peak [Ca2+]c.
oxidative phosphorylation; exercise; contractions; caffeine; relaxation; excitation-contraction coupling
This article has been cited by other articles:
|
|
 |
|
  T. Sonobe, T. Inagaki, D. C. Poole, and Y. Kano Intracellular calcium accumulation following eccentric contractions in rat skeletal muscle in vivo: role of stretch-activated channels Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2008; 294(4): R1329 - R1337. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Amann and J. A. L. Calbet Convective oxygen transport and fatigue J Appl Physiol, March 1, 2008; 104(3): 861 - 870. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 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]
|
|
|
|
 |
|
 R. A. Howlett and M. C. Hogan Muscle: Effect of hypoxia on fatigue development in rat muscle composed of different fibre types Exp Physiol, September 1, 2007; 92(5): 887 - 894. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Walsh, R. A. Howlett, C. M. Stary, C. A. Kindig, and M. C. Hogan Measurement of activation energy and oxidative phosphorylation onset kinetics in isolated muscle fibers in the absence of cross-bridge cycling Am J Physiol Regulatory Integrative Comp Physiol, June 1, 2006; 290(6): R1707 - R1713. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. GISSEL The Role of Ca2+ in Muscle Cell Damage Ann. N.Y. Acad. Sci., December 1, 2005; 1066(1): 166 - 180. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. A Howlett, K. M Kelley, B. Grassi, L. B. Gladden, and M. C Hogan Caffeine administration results in greater tension development in previously fatigued canine muscle in situ Exp Physiol, November 1, 2005; 90(6): 873 - 879. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. M. Stary and M. C. Hogan Intracellular pH during sequential, fatiguing contractile periods in isolated single Xenopus skeletal muscle fibers J Appl Physiol, July 1, 2005; 99(1): 308 - 312. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. A. Kindig, R. A. Howlett, C. M. Stary, B. Walsh, and M. C. Hogan Effects of acute creatine kinase inhibition on metabolism and tension development in isolated single myocytes J Appl Physiol, February 1, 2005; 98(2): 541 - 549. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. A. Kindig, C. M. Stary, and M. C. Hogan Effect of dissociating cytosolic calcium and metabolic rate on intracellular PO2 kinetics in single frog myocytes J. Physiol., January 15, 2005; 562(2): 527 - 534. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Rob. S. James, R. S. Wilson, and G. N. Askew Effects of caffeine on mouse skeletal muscle power output during recovery from fatigue J Appl Physiol, February 1, 2004; 96(2): 545 - 552. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Kohin, C. M. Stary, R. A. Howlett, and M. C. Hogan Preconditioning improves function and recovery of single muscle fibers during severe hypoxia and reoxygenation Am J Physiol Cell Physiol, July 1, 2001; 281(1): C142 - C146. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. A. Howlett, C. M. Stary, and M. C. Hogan Recovery of force during postcontractile depression in single Xenopus muscle fibers Am J Physiol Regulatory Integrative Comp Physiol, May 1, 2001; 280(5): R1469 - R1475. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
