Control of respiration and bioenergetics during muscle contraction
Control of respiration and bioenergetics during muscle contraction
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DOI：
10.1152/ajpcell.00138.2004
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发表时间：
2005-03-01
影响因子：
5.5
通讯作者：
Jue, T
中科院分区：
文献类型：
--
作者：
Chung, YR;Molé, PA;Jue, T
1H-1-NMR实验测定了在0.75、0.92和1.17 Hz恒定负荷下进行跖屈运动时，人小腿肌肉中氧合肌红蛋白（MbO（2））去饱和动力学的细胞内O-2消耗（（V）/点O-2）。在肌肉收缩开始时，肌红蛋白（Mb）迅速去饱和。类似于30 s的去饱和速率常数反映了细胞内（V）对点O-2。虽然Mb在所有工作负载水平下以类似的时间常数快速去饱和，但其最终稳态水平不同。随着功的增加，最终稳态细胞PO 2逐渐减少。然而，在Mb去饱和达到稳定状态后，O-2上的（V）继续上升。在当前呼吸控制模型的基础上，本报告中的分析揭示了两个不同的（V）过点O-2阶段：收缩开始时的ADP非依赖性阶段和Mb达到稳态后的ADP依赖性阶段。与公认的观点相反，最初的细胞内（V）超过点O-2显示氧化磷酸化可以支持高达36%的能量成本，比预期的分数高得多。分配的能量通量表明，31%的非氧化成分存在，并响应于动态能量利用-恢复周期（仅持续几毫秒）假设在糖原分流理论。本研究提供了在肌肉收缩过程中呼吸，生物能量学和肌红蛋白功能的调节的观点。
H-1-NMR experiments have determined intracellular O-2 consumption ((V) over dot O-2) 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 similar to 30 s reflects the intracellular (V) over dot O-2. 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, (V) over dot O-2 continues to rise. On the basis of current respiratory control models, the analysis in the present report reveals two distinct (V) over dot O-2 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 (V) over dot O-2 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.