Francescato Maria Pia, Cettolo Valentina, di Prampero Pietro Enrico
Department of Biomedical Sciences and Technologies and M.A.T.I. Centre of Excellence, University of Udine, Udine, Italy.
J Appl Physiol (1985). 2008 Jul;105(1):158-64. doi: 10.1152/japplphysiol.00007.2008. Epub 2008 Apr 24.
At the onset of a square-wave exercise of moderate intensity, in the absence of any detectable lactate production, the hydrolysis of phosphocreatine (PCr) fills the gap between energy requirement and energy yield by oxidative pathways, thus representing a readily available source of energy for the muscle. We verified experimentally the relationships between high-energy phosphates and/or their changes and the time constant of PCr concentration ([PCr]) kinetics in humans (tau(PCr)). High-energy phosphate concentration (by (31)P-NMR spectroscopy) in the calf muscles were measured during three repetitions of the rest-to-work transition of moderate aerobic square-wave exercise on nine healthy volunteers, while resting [PCr] was estimated from the appropriate spectroscopy data. PCr concentration decreased significantly (22 +/- 6%) from rest to steady-state exercise, without differences among the three repetitions. Absolute resting [PCr] and tau(PCr) were consistent with literature values, amounting to 27.5 +/- 2.2 mM and 23.9 +/- 2.9 s, respectively. No significant relationships were detected between individual tau(PCr) and mechanical power, fraction or absolute amount of PCr hydrolyzed, or change in ADP concentration. On the contrary, individual tau(PCr) (s) was linearly related to absolute resting [PCr] (mM), the relationship being described by: tau(PCr) = 0.656 + 0.841.[PCr] (n = 9, R = 0.708, P < 0.05). These data support the view that in humans PCr concentration sets the time course of the oxidative metabolism in skeletal muscle at the start of exercise, being one of the main controllers of oxidative phosphorylation.
在中等强度方波运动开始时，在没有任何可检测到的乳酸生成的情况下，磷酸肌酸（PCr）的水解填补了能量需求与氧化途径能量产生之间的差距，因此代表了肌肉易于利用的能量来源。我们通过实验验证了人体中高能磷酸盐及其变化与PCr浓度（[PCr]）动力学时间常数（tau(PCr)）之间的关系。在九名健康志愿者进行三次中等强度有氧方波运动从休息到工作转换的重复过程中，通过（31）P-NMR光谱法测量小腿肌肉中的高能磷酸盐浓度，同时根据适当的光谱数据估算静息[PCr]。从休息到稳态运动，PCr浓度显著下降（22±6%），三次重复之间无差异。静息[PCr]绝对值和tau(PCr)与文献值一致，分别为27.5±2.2 mM和23.9±2.9 s。未检测到个体tau(PCr)与机械功率、PCr水解的分数或绝对量或ADP浓度变化之间存在显著关系。相反，个体tau(PCr)（秒）与静息[PCr]绝对值（mM）呈线性相关，该关系描述为：tau(PCr)=0.656 + 0.841·[PCr]（n = 9，R = 0.708，P < 0.05）。这些数据支持这样一种观点，即在人类中，PCr浓度在运动开始时设定了骨骼肌氧化代谢的时间进程，是氧化磷酸化的主要控制因素之一。
