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

This Article Full Text Free Full Text (PDF) Free All Versions of this Article: 98/2/541    most recent 00354.2004v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science 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 ISI Web of Science (22) Citing Articles via Google Scholar Google Scholar Articles by Kindig, C. A. Articles by Hogan, M. C. Search for Related Content PubMed PubMed Citation Articles by Kindig, C. A. Articles by Hogan, M. C.

Effects of acute creatine kinase inhibition on metabolism and tension development in isolated single myocytes

University of California-San Diego, Department of Medicine, Physiology Division, La Jolla, California

Submitted 1 April 2004 ; accepted in final form 22 July 2004

This study investigated the effects of acute creatine kinase (CK) inhibition (CK_i) on contractile performance, cytosolic Ca²⁺ concentration ([Ca²⁺]_c), and intracellular PO₂ (PI) in Xenopus laevis isolated myocytes during a 2-min bout of isometric tetanic contractions (0.33-Hz frequency). Peak tension was similar between trials during the first contraction but was significantly (P < 0.05) attenuated for all subsequent contractions in CK_i vs. control (Con). The fall in PI(PI) from resting values was significantly greater in Con (26.0 ± 2.2 Torr) compared with CK_i (17.8 ± 1.8 Torr). However, the ratios of Con to CK_i end-peak tension (1.53 ± 0.11) and PI(1.49 ± 0.11) were similar, suggesting an unaltered aerobic cost of contractions. Additionally, the mean response time (MRT) of PIwas significantly faster in CK_i vs. Con during both the onset (31.8 ± 5.5 vs. 49.3 ± 5.7 s; P < 0.05) and cessation (21.2 ± 4.1 vs. 68.0 ± 3.2 s; P < 0.001) of contractions. These data demonstrate that initial phosphocreatine hydrolysis in single skeletal muscle fibers is crucial for maintenance of sarcoplasmic reticulum Ca²⁺ release and peak tension during a bout of repetitive tetanic contractions. Furthermore, as PIfell more rapidly at contraction onset in CK_i compared with Con, these data suggest that CK activity temporally buffers the initial ATP-to-ADP concentration ratio at the transition to an augmented energetic demand, thereby slowing the initial mitochondrial activation by mitigating the energetic control signal (i.e., ADP concentration, phosphorylation potential, etc.) between sites of ATP supply and demand.

oxygen consumption; muscle energetics; skeletal muscle fiber

This article has been cited by other articles:

				B. Walsh, C. M. Stary, R. A. Howlett, K. M. Kelley, and M. C. Hogan Glycolytic activation at the onset of contractions in isolated Xenopus laevis single myofibres Exp Physiol, September 1, 2008; 93(9): 1076 - 1084. [Abstract] [Full Text] [PDF]

				A. R. Barker, J. R. Welsman, J. Fulford, D. Welford, and N. Armstrong Muscle phosphocreatine kinetics in children and adults at the onset and offset of moderate-intensity exercise J Appl Physiol, August 1, 2008; 105(2): 446 - 456. [Abstract] [Full Text] [PDF]

				M. P. Francescato, V. Cettolo, and P. E. di Prampero Influence of phosphagen concentration on phosphocreatine breakdown kinetics. Data from human gastrocnemius muscle J Appl Physiol, July 1, 2008; 105(1): 158 - 164. [Abstract] [Full Text] [PDF]

				B. J. Gurd, S. J. Peters, G. J. F. Heigenhauser, P. J. LeBlanc, T. J. Doherty, D. H. Paterson, and J. M. Kowalchuk O2 uptake kinetics, pyruvate dehydrogenase activity, and muscle deoxygenation in young and older adults during the transition to moderate-intensity exercise Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2008; 294(2): R577 - R584. [Abstract] [Full Text] [PDF]

				A. M. Jones, D. P. Wilkerson, and J. Fulford Muscle [phosphocreatine] dynamics following the onset of exercise in humans: the influence of baseline work-rate J. Physiol., February 1, 2008; 586(3): 889 - 898. [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]

				B. Glancy, T. Barstow, and W. T. Willis Linear relation between time constant of oxygen uptake kinetics, total creatine, and mitochondrial content in vitro Am J Physiol Cell Physiol, January 1, 2008; 294(1): C79 - C87. [Abstract] [Full Text] [PDF]

				A. M. Jones, D. P. Wilkerson, N. J. Berger, and J. Fulford Influence of endurance training on muscle [PCr] kinetics during high-intensity exercise Am J Physiol Regulatory Integrative Comp Physiol, July 1, 2007; 293(1): R392 - R401. [Abstract] [Full Text] [PDF]

				P. McDonough, B. J. Behnke, D. J. Padilla, T. I. Musch, and D. C. Poole Respiratory: Control of microvascular oxygen pressures during recovery in rat fast-twitch muscle of differing oxidative capacity Exp Physiol, July 1, 2007; 92(4): 731 - 738. [Abstract] [Full Text] [PDF]

				R. A. Howlett, C. A. Kindig, and M. C. Hogan Intracellular PO2 kinetics at different contraction frequencies in Xenopus single skeletal muscle fibers J Appl Physiol, April 1, 2007; 102(4): 1456 - 1461. [Abstract] [Full Text] [PDF]

				B. J. Gurd, S. J. Peters, G. J. F. Heigenhauser, P. J. LeBlanc, T. J. Doherty, D. H. Paterson, and J. M. Kowalchuk Prior heavy exercise elevates pyruvate dehydrogenase activity and speeds O2 uptake kinetics during subsequent moderate-intensity exercise in healthy young adults J. Physiol., December 15, 2006; 577(3): 985 - 996. [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]

				V. Saks, P. Dzeja, U. Schlattner, M. Vendelin, A. Terzic, and T. Wallimann Cardiac system bioenergetics: metabolic basis of the Frank-Starling law J. Physiol., March 1, 2006; 571(2): 253 - 273. [Abstract] [Full Text] [PDF]

				D. P Wilkerson, J. Rittweger, N. J. A Berger, P. F Naish, and A. M Jones Influence of recombinant human erythropoietin treatment on pulmonary O2 uptake kinetics during exercise in humans J. Physiol., October 15, 2005; 568(2): 639 - 652. [Abstract] [Full Text] [PDF]

				L. F. Ferreira, B. J. Lutjemeier, D. K. Townsend, and T. J. Barstow Dynamics of skeletal muscle oxygenation during sequential bouts of moderate exercise Exp Physiol, May 1, 2005; 90(3): 393 - 401. [Abstract] [Full Text] [PDF]