Kemp G J, Thompson C H, Taylor D J, Radda G K
Medical Research Council Biochemical and Clinical Magnetic Resonance Unit, Oxford Radcliffe Hospital, UK.
Eur J Appl Physiol Occup Physiol. 1997;76(5):462-71. doi: 10.1007/s004210050276.
In recovery from exercise, phosphocreatine resynthesis results in the net generation of protons, while the net efflux of protons restores pH to resting values. Because proton efflux rate declines as pH increases, it appears to have an approximately linear pH-dependence. We set out to examine this in detail using recovery data from human calf muscle. Proton efflux rates were calculated from changes in pH and phosphocreatine concentration, measured by 31P magnetic resonance spectroscopy, after incremental dynamic exercise to exhaustion. Results were collected post hoc into five groups on the basis of end-exercise pH. Proton efflux rates declined approximately exponentially with time. These were rather similar in all groups, even when pH changes were small, so that the apparent rate constant (the ratio of efflux rate to pH change) varied widely. However, all groups showed a consistent pattern of decrease with time; the halftimes of both proton efflux rate and the apparent rate constant were longer at lower pH. At each time-point, proton efflux rates showed a significant pH-dependence [slope 17 (3) mmol x l(-1) x min(-1) x pH unit(-1) at the start of recovery, mean (SEM)], but also a significant intercept at resting pH [16 (3) mmol x l(-1) x min(-1) at the start of recovery]. The intercept and the slope both decreased with time, with halftimes of 0.37 (0.06) and 1.4 (0.4) min, respectively. We conclude that over a wide range of end-exercise pH, net proton efflux during recovery comprises pH-dependent and pH-independent components, both of which decline with time. Comparison with other data in the literature suggests that lactate/proton cotransport can be only a small component of this initial recovery proton efflux.
在运动恢复过程中，磷酸肌酸的重新合成会导致质子的净生成，而质子的净流出则使pH值恢复到静息值。由于质子流出速率随pH值升高而下降，因此它似乎与pH值呈近似线性关系。我们着手使用来自人类小腿肌肉的恢复数据对此进行详细研究。通过31P磁共振波谱法测量递增动态运动至力竭后pH值和磷酸肌酸浓度的变化，计算质子流出速率。根据运动结束时的pH值，事后将结果分为五组。质子流出速率随时间大致呈指数下降。在所有组中，即使pH值变化很小，情况也相当相似，因此表观速率常数（流出速率与pH值变化的比值）差异很大。然而，所有组均显示出随时间一致的下降模式；在较低pH值下，质子流出速率和表观速率常数的半衰期均较长。在每个时间点，质子流出速率均显示出显著的pH依赖性[恢复开始时斜率为17(3) mmol·L-1·min-1·pH单位-1，均值(SEM)]，但在静息pH值时也有显著截距[恢复开始时为16(3) mmol·L-1·min-1]。截距和斜率均随时间下降，半衰期分别为0.37(0.06)和1.4(0.4)分钟。我们得出结论，在运动结束时的广泛pH值范围内，恢复过程中的净质子流出包括pH依赖性和pH非依赖性成分，两者均随时间下降。与文献中的其他数据比较表明，乳酸/质子协同转运可能只是这种初始恢复质子流出的一小部分。
