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

This Article Full Text 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 Westerblad, H. Articles by Lännergren, J. Search for Related Content PubMed PubMed Citation Articles by Westerblad, H. Articles by Lännergren, J.

Mechanisms underlying reduced maximum shortening velocity during fatigue of intact, single fibres of mouse muscle

Håkan Westerblad, Anders J. Dahlstedt and Jan Lännergren

1. The mechanism behind the reduction in shortening velocity in skeletal muscle fatigue is unclear. In the present study we have measured the maximum shortening velocity (V₀) with slack tests during fatigue produced by repeated, 350 ms tetani in intact, single muscle fibres from the mouse. We have focused on two possible mechanisms behind the reduction in V₀: reduced tetanic Ca²⁺ and accumulation of ADP.

2. During fatigue V₀ initially declined slowly, reaching 90 % of the control after about forty tetani. The rate of decline then increased and V₀ fell to 70 % of the control in an additional twenty tetani. The reduction in isometric force followed a similar pattern.

3. Exposing unfatigued fibres to 10 µM dantrolene, which reduces tetanic Ca²⁺, lowered force by about 35 % but had no effect on V₀.

4. In order to see if ADP might increase rapidly during ongoing contractions, we used a protocol with a tetanus of longer duration bracketed by standard-duration tetani. V₀ in these three tetani were not significantly different in control, whereas V₀ was markedly lower in the longer tetanus during fatigue and in unfatigued fibres where the creatine kinase reaction was inhibited by 10 µM dinitrofluorobenzene.

5. We conclude that the reduction in V₀ during fatigue is mainly due to a transient accumulation of ADP, which develops during contractions in fibres with impaired phosphocreatine energy buffering.

This article has been cited by other articles:

				J. A. Zoladz, L. B. Gladden, M. C. Hogan, Z. Nieckarz, and B. Grassi Progressive recruitment of muscle fibers is not necessary for the slow component of VO2 kinetics J Appl Physiol, August 1, 2008; 105(2): 575 - 580. [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]

				C. Reggiani When fibres go slack and cross bridges are free to run: a brilliant method to study kinetic properties of acto-myosin interaction J. Physiol., August 15, 2007; 583(1): 5 - 7. [Full Text] [PDF]

				H. Fischer, M. Esbjornsson, R. L. Sabina, A. Stromberg, M. Peyrard-Janvid, and B. Norman AMP deaminase deficiency is associated with lower sprint cycling performance in healthy subjects J Appl Physiol, July 1, 2007; 103(1): 315 - 322. [Abstract] [Full Text] [PDF]

				D. A. Jones, C. J. de Ruiter, and A. de Haan Change in contractile properties of human muscle in relationship to the loss of power and slowing of relaxation seen with fatigue J. Physiol., November 1, 2006; 576(3): 913 - 922. [Abstract] [Full Text] [PDF]

				A. J. Cheng and C. L. Rice Fatigue and recovery of power and isometric torque following isotonic knee extensions J Appl Physiol, October 1, 2005; 99(4): 1446 - 1452. [Abstract] [Full Text] [PDF]

				C. R. Hancock, E. Janssen, and R. L. Terjung Skeletal muscle contractile performance and ADP accumulation in adenylate kinase-deficient mice Am J Physiol Cell Physiol, June 1, 2005; 288(6): C1287 - C1297. [Abstract] [Full Text] [PDF]

				C. R. Hancock, J. J. Brault, R. W. Wiseman, R. L. Terjung, and R. A. Meyer 31P-NMR observation of free ADP during fatiguing, repetitive contractions of murine skeletal muscle lacking AK1 Am J Physiol Cell Physiol, June 1, 2005; 288(6): C1298 - C1304. [Abstract] [Full Text] [PDF]

				K. A. P. Edman Contractile properties of mouse single muscle fibers, a comparison with amphibian muscle fibers J. Exp. Biol., May 15, 2005; 208(10): 1905 - 1913. [Abstract] [Full Text] [PDF]

				R. M. Murphy, D. G. Stephenson, and G. D. Lamb Effect of creatine on contractile force and sensitivity in mechanically skinned single fibers from rat skeletal muscle Am J Physiol Cell Physiol, December 1, 2004; 287(6): C1589 - C1595. [Abstract] [Full Text] [PDF]

				T. D. Noakes, J. A. L. Calbet, R. Boushel, H. Sondergaard, G. Radegran, P. D. Wagner, and B. Saltin Central regulation of skeletal muscle recruitment explains the reduced maximal cardiac output during exercise in hypoxia Am J Physiol Regulatory Integrative Comp Physiol, October 1, 2004; 287(4): R996 - R1002. [Full Text] [PDF]

				J. A. L. Calbet, J. A. De Paz, N. Garatachea, S. Cabeza de Vaca, and J. Chavarren Anaerobic energy provision does not limit Wingate exercise performance in endurance-trained cyclists J Appl Physiol, February 1, 2003; 94(2): 668 - 676. [Abstract] [Full Text] [PDF]

				B. Norman, R. L. Sabina, and E. Jansson Regulation of skeletal muscle ATP catabolism by AMPD1 genotype during sprint exercise in asymptomatic subjects J Appl Physiol, July 1, 2001; 91(1): 258 - 264. [Abstract] [Full Text] [PDF]

				B. T. Ameredes, W.-Z. Zhan, Y. S. Prakash, R. Vandenboom, and G. C. Sieck Power fatigue of the rat diaphragm muscle J Appl Physiol, December 1, 2000; 89(6): 2215 - 2219. [Abstract] [Full Text] [PDF]

				A. J. DAHLSTEDT, A. KATZ, B. WIERINGA, and H. WESTERBLAD Is creatine kinase responsible for fatigue? Studies of isolated skeletal muscle deficient in creatine kinase FASEB J, May 1, 2000; 14(7): 982 - 990. [Abstract] [Full Text]