Smith Sinclair A, Montain Scott J, Zientara Gary P, Fielding Roger A
Temple University, Neuromuscular Function Laboratory, Department of Occupational Therapy, 3307 North Broad St., Philadelphia, PA 19140, USA.
J Appl Physiol (1985). 2004 Jun;96(6):2288-92. doi: 10.1152/japplphysiol.01021.2003. Epub 2004 Feb 20.
Recent human isolated muscle fiber studies suggest that phosphocreatine (PCr) and creatine (Cr) concentrations play a role in the regulation of mitochondrial respiration rate. To determine whether similar regulatory mechanisms are present in vivo, this study examined the relationship between skeletal muscle mitochondrial respiration rate and end-exercise PCr, Cr, PCr-to-Cr ratio (PCr/Cr), ADP, and pH by using (31)P-magnetic resonance spectroscopy in 16 men and women (36.9 +/- 4.6 yr). The initial PCr resynthesis rate and time constant (T(c)) were used as indicators of mitochondrial respiration after brief (10-12 s) and exhaustive (1-4 min) dynamic knee extension exercise performed in placebo and creatine-supplemented conditions. The results show that the initial PCr resynthesis rate has a strong relationship with end-exercise PCr, Cr, and PCr/Cr (r > 0.80, P < 0.001), a moderate relationship with end-exercise ADP (r = 0.77, P < 0.001), and no relationship with end-exercise pH (r = -0.14, P = 0.34). The PCr T(c) was not as strongly related to PCr, Cr, PCr/Cr, and ADP (r < 0.77, P < 0.001-0.18) and was significantly influenced by end-exercise pH (r = -0.43, P < 0.01). These findings suggest that end-exercise PCr and Cr should be taken into consideration when PCr recovery kinetics is used as an indicator of mitochondrial respiration and that the initial PCr resynthesis rate is a more reliable indicator of mitochondrial respiration compared with the PCr T(c).
近期针对人体分离肌纤维的研究表明，磷酸肌酸（PCr）和肌酸（Cr）浓度在调节线粒体呼吸速率中发挥作用。为了确定体内是否存在类似的调节机制，本研究通过对16名男性和女性（36.9±4.6岁）使用磷-31磁共振波谱法，检测了骨骼肌线粒体呼吸速率与运动结束时的PCr、Cr、PCr与Cr的比值（PCr/Cr）、ADP及pH之间的关系。在安慰剂和补充肌酸的条件下，进行短暂（10 - 12秒）和力竭（1 - 4分钟）的动态伸膝运动后，将初始PCr再合成速率和时间常数（T(c)）用作线粒体呼吸的指标。结果显示，初始PCr再合成速率与运动结束时的PCr、Cr和PCr/Cr密切相关（r > 0.80，P < 0.001），与运动结束时的ADP中度相关（r = 0.77，P < 0.001），而与运动结束时的pH无关（r = -0.14，P = 0.34）。PCr的T(c)与PCr、Cr、PCr/Cr和ADP的相关性不强（r < 0.77，P < 0.001 - 0.18），且受到运动结束时pH的显著影响（r = -0.43，P < 0.01）。这些发现表明，当将PCr恢复动力学用作线粒体呼吸的指标时，应考虑运动结束时的PCr和Cr，并且与PCr的T(c)相比，初始PCr再合成速率是线粒体呼吸更可靠的指标。
