| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Biological Chemistry, University of California Davis, Davis, CA, USA
2 Exercise Science, University of California Davis, Davis, CA, USA
3 GE Medical Systems, Inc., Fremont, CA, USA
* To whom correspondence should be addressed. E-mail: tjue{at}ucdavis.edu.
1H NMR experiments have determined the intracellular VO2 with the oxymyoglobin (MbO2) desaturation kinetics in human calf muscle during plantar flexion exercise at 0.75, 0.92, and 1.17 Hz with a constant load. At the onset of muscle contraction, the myoglobin (Mb) desaturates rapidly. The desaturation rate constant of ~30s reflects the intracellular VO2. Although Mb desaturates quickly with a similar time constant at all workload, its final steady state level differs. As work increases, the final steady state cellular PO2 decreases progressively. After Mb desaturation has reached a steady state, however, VO2 still continues to rise. Based on current respiratory control models, the analysis reveals two distinct oxygen consumption (VO2) phases: an ADP independent phase at the onset of contraction and an ADP dependent phase after Mb has reached a steady state. In contrast to the accepted view, the initial intracellular VO2 shows that oxidative phosphorylation can support up to the 36% of the energy cost, a significantly higher fraction than expected. Partitioning the energy flux shows that a 31% non-oxidative component exists and responds to the dynamic millisecond energy utilization/restoration cycle, as postulated in the glycogen shunt theory. The study casts perspectives on the regulation of respiration, bioenergetics, and Mb function during muscle contraction.
This article has been cited by other articles:
|
|
 |
|
  S. A. Jubrias, N. K. Vollestad, R. K. Gronka, and M. J. Kushmerick Contraction coupling efficiency of human first dorsal interosseous muscle J. Physiol., April 1, 2008; 586(7): 1993 - 2002. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. Lai, G. M. Saidel, B. Grassi, L. B. Gladden, and M. E. Cabrera Model of oxygen transport and metabolism predicts effect of hyperoxia on canine muscle oxygen uptake dynamics J Appl Physiol, October 1, 2007; 103(4): 1366 - 1378. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P.-C. Lin, U. Kreutzer, and T. Jue Myoglobin translational diffusion in rat myocardium and its implication on intracellular oxygen transport J. Physiol., January 15, 2007; 578(2): 595 - 603. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Chung, S.-J. Huang, A. Glabe, and T. Jue Implication of CO inactivation on myoglobin function Am J Physiol Cell Physiol, June 1, 2006; 290(6): C1616 - C1624. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Chung Oxygen reperfusion is limited in the postischemic hypertrophic myocardium Am J Physiol Heart Circ Physiol, May 1, 2006; 290(5): H2075 - H2084. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. S. Richardson, S. Duteil, C. Wary, D. W. Wray, J. Hoff, and P. G. Carlier Human skeletal muscle intracellular oxygenation: the impact of ambient oxygen availability J. Physiol., March 1, 2006; 571(2): 415 - 424. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
