Abstract
H-NMR experiments have determined intracellular O 2 consumption (V̇ O2) with oxymyoglobin (MbO 2) 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 ∼30 s reflects the intracellular V̇ O2. 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 P O2 decreases progressively. After Mb desaturation has reached a steady state, however, V̇ O2 continues to rise. On the basis of current respiratory control models, the analysis in the present report reveals two distinct V̇ O2 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 V̇ O2 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.
| Original language | English (US) |
|---|---|
| Journal | American Journal of Physiology - Cell Physiology |
| Volume | 288 |
| Issue number | 3 57-3 |
| DOIs | |
| State | Published - Mar 2005 |
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Keywords
- Exercise
- Glycogen
- Myoglobin
- Nuclear magnetic resonance
- Oxygen
ASJC Scopus subject areas
- Clinical Biochemistry
- Cell Biology
- Physiology
Cite this
Control of respiration and bioenergetics during muscle contraction. / Chung, Youngran; Molé, Paul A.; Sailasuta, Napapon; Tuan, Khanh Tran; Hurd, Ralph; Jue, Thomas.
In: American Journal of Physiology - Cell Physiology, Vol. 288, No. 3 57-3, 03.2005.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Control of respiration and bioenergetics during muscle contraction
AU - Chung, Youngran
AU - Molé, Paul A.
AU - Sailasuta, Napapon
AU - Tuan, Khanh Tran
AU - Hurd, Ralph
AU - Jue, Thomas
PY - 2005/3
Y1 - 2005/3
N2 - H-NMR experiments have determined intracellular O 2 consumption (V̇ O2) with oxymyoglobin (MbO 2) 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 ∼30 s reflects the intracellular V̇ O2. 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 P O2 decreases progressively. After Mb desaturation has reached a steady state, however, V̇ O2 continues to rise. On the basis of current respiratory control models, the analysis in the present report reveals two distinct V̇ O2 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 V̇ O2 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.
AB - H-NMR experiments have determined intracellular O 2 consumption (V̇ O2) with oxymyoglobin (MbO 2) 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 ∼30 s reflects the intracellular V̇ O2. 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 P O2 decreases progressively. After Mb desaturation has reached a steady state, however, V̇ O2 continues to rise. On the basis of current respiratory control models, the analysis in the present report reveals two distinct V̇ O2 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 V̇ O2 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.
KW - Exercise
KW - Glycogen
KW - Myoglobin
KW - Nuclear magnetic resonance
KW - Oxygen
UR - http://www.scopus.com/inward/record.url?scp=13644270256&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=13644270256&partnerID=8YFLogxK
U2 - 10.1152/ajpcell.00138.2004
DO - 10.1152/ajpcell.00138.2004
M3 - Article
C2 - 15537712
AN - SCOPUS:13644270256
VL - 288
JO - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
JF - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
SN - 1931-857X
IS - 3 57-3
ER -