Binzoni T, Ferretti G, Schenker K, Cerretelli P
Department of Physiology, Centre Médical Universitaire, Geneva, Switzerland.
J Appl Physiol (1985). 1992 Oct;73(4):1644-9. doi: 10.1152/jappl.1992.73.4.1644.
The kinetics of phosphocreatine (PC) breakdown in human plantar flexors at the onset of constant-load aerobic exercise was determined by high-resolution 31P-nuclear magnetic resonance spectroscopy (NMRS). The half time of the process (t1/2PC) was obtained by fitting curves (n = 13) from five subjects at various aerobic work loads for which muscle pH was not different from that at rest. Steady-state PC concentration ([PC]) was not < 70% of the resting value and was linearly related to the work load (w) ([PC] = -3.01 +/- 0.08 w + 1 (r = 0.48, 2P < 0.1)). The average t1/2PC was 16.2 s and was independent of work load. Because the half time of the muscle PC kinetics reflects the half time of the O2 uptake (MO2) kinetics (t1/2MO2), the latter is equal to that found earlier in the isolated perfused dog gastrocnemius. Whereas in the dog the above t1/2MO2 compares well with the homologous half time of the O2 uptake at the alveolar level, in humans such equivalence is found only at extremely low work loads, when the transient contribution by anaerobic glycolysis is negligible.
采用高分辨率31P核磁共振波谱法（NMRS）测定了人体在进行恒定负荷有氧运动开始时，足底屈肌中磷酸肌酸（PC）分解的动力学。通过对5名受试者在不同有氧工作负荷下的曲线（n = 13）进行拟合，得到该过程的半衰期（t1/2PC），这些工作负荷下的肌肉pH值与静息时无异。稳态PC浓度（[PC]）不低于静息值的70%，且与工作负荷（w）呈线性相关（[PC] = -3.01 +/- 0.08 w + 1，r = 0.48，2P < 0.1）。平均t1/2PC为16.2秒，且与工作负荷无关。由于肌肉PC动力学的半衰期反映了摄氧量（MO2）动力学的半衰期（t1/2MO2），因此后者与之前在离体灌注的犬腓肠肌中发现的半衰期相等。然而，在犬类中，上述t1/2MO2与肺泡水平摄氧量的同源半衰期比较吻合，而在人类中，只有在极低工作负荷下，当无氧糖酵解的短暂贡献可忽略不计时，才会出现这种等效性。
