Chung 2005 Am J Physiol Cell Physiol
| Chung Y, Molé PA, Sailasuta N, Tran TK, Hurd R, Jue T (2005) Control of respiration and bioenergetics during muscle contraction. https://doi.org/10.1152/ajpcell.00138.2004 |
» Am J Physiol Cell Physiol 288:C730-8. PMID: 15537712 Open Access
Chung Y, Mole PA, Sailasuta N, Tran TK, Hurd R, Jue T (2005) Am J Physiol Cell Physiol
Abstract: 1H-NMR experiments have determined intracellular O2 consumption (VO2) with 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, myoglobin (Mb) desaturates rapidly. The desaturation rate constant of approximately 30 s reflects the intracellular VO2. Although Mb desaturates quickly with a similar time constant at all workload levels, 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 continues to rise. On the basis of current respiratory control models, the analysis in the present report reveals two distinct 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 36 % of the energy cost, a significantly higher fraction than expected. Partitioning of the energy flux shows that a 31 % nonoxidative component exists and responds to the dynamic energy utilization-restoration cycle (which lasts for only milliseconds) as postulated in the glycogen shunt theory. The present study offers perspectives on the regulation of respiration, bioenergetics, and Mb function during muscle contraction.
• Bioblast editor: Gnaiger E
Labels: MiParea: Respiration, Exercise physiology;nutrition;life style
Stress:Hypoxia Organism: Human Tissue;cell: Skeletal muscle
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