| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Department of Medicine, Physiology Division, University of California-San Diego, La Jolla, CA, USA
* To whom correspondence should be addressed. E-mail: bjwalsh{at}ucsd.edu.
The purpose of this investigation was to study the effects of acute creatine kinase (CK) inhibition (CKi) on contractile performance, cytosolic [Ca2+] ([Ca2+]c), and intracellular PO2 (PiO2) in Xenopus laevis isolated single myocytes during a 2-min bout of isometric tetanic contractions (0.33 Hz frequency). [Ca2+]c was measured via ratiometric fluorescence microscopy and PiO2 via phosphorescence quenching techniques. Peak tension was not significantly (p>0.05) different between CKi and CON trials during the first contraction. However, peak tension fell significantly (p<0.05) during the 2nd contraction with CKi and remained attenuated compared to CON for the remainder of the contraction bout. The reduction in peak tension seen after the first contraction was associated with a significant reduction in peak [Ca2+]c. There was a significantly greater fall in PiO2 from resting values in CON (26.0 ± 2.2 mmHg) compared to CKi (17.8 ± 1.8 mmHg). However, as end peak tension was reduced in CKi compared to CON, the ratio of CON-to-CKi end peak tension (1.53 ± 0.11) was not different to the ratio of CON-to-CKi PiO2 fall with contractions (1.49 ± 0.11), suggesting an unaltered aerobic cost of contractions between trials. In addition, the speed of the fall in PiO2 at contractions onset, assessed via the time to 63% of the overall PiO2 fall (i.e., mean response time [MRT]) was significantly faster (p<0.05) in the CKi compared to CON trial (CKi = 31.8 ± 5.5 s; CON = 49.3 ± 5.7). Similarly, the speed of the PiO2 recovery following contraction cessation was significantly faster (CKi MRT = 21.2 ± 4.1 s; CON MRT = 68.0 ± 3.2; p<0.001) in the CKi compared to the CON trial. These data demonstrate that initial PCr hydrolysis in single skeletal muscle fibers is crucial for maintenance of SR Ca2+ release and peak tension during a bout of repetitive tetanic contractions. Furthermore, as PiO2 fell more rapidly at contractions onset in the CKi trial compared to CON, these data suggest CK activity buffers temporally the initial [ATP]/[ADP] at the transition to an augmented energetic demand, thereby slowing the initial mitochondrial activation by mitigating the energetic control signal (i.e., [ADP], phosphorylation potential, etc.) between sites of ATP supply and demand.
This article has been cited by other articles:
|
|
 |
|
  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 muscle oxygenation and speeds O2 uptake kinetics during moderate exercise in older adults Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2009; 297(3): R877 - R884. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. R. McKay, D. H. Paterson, and J. M. Kowalchuk Effect of short-term high-intensity interval training vs. continuous training on O2 uptake kinetics, muscle deoxygenation, and exercise performance J Appl Physiol, July 1, 2009; 107(1): 128 - 138. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. M. Jones, D. P. Wilkerson, and J. Fulford Influence of dietary creatine supplementation on muscle phosphocreatine kinetics during knee-extensor exercise in humans Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2009; 296(4): R1078 - R1087. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Vanhatalo and A. M. Jones Influence of prior sprint exercise on the parameters of the \#8216;all-out critical power test' in men Exp Physiol, February 1, 2009; 94(2): 255 - 263. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
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 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]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
