McCreary C R, Chilibeck P D, Marsh G D, Paterson D H, Cunningham D A, Thompson R T
Department of Nuclear Medicine, Lawson Research Institute, St. Joseph's Health Centre, London, Ontario, Canada.
J Appl Physiol (1985). 1996 Sep;81(3):1331-8. doi: 10.1152/jappl.1996.81.3.1331.
The purpose of this study is to directly compare the dynamic responses of phosphocreatine (PCr) and P(i) to those oxygen uptake (VO2) measured at the lung during transitions to and from moderate-intensity exercise. Changes in PCr and P(i) were measured by 31P-nuclear magnetic resonance spectroscopy, and changes in VO2 were measured breath by breath by mass spectroscopy during transitions to and from moderate-intensity square-wave ankle plantar flexion exercise in 11 subjects (7 men and 4 women; mean age 27 yr). Three repeated transitions were averaged for improvement in signal-to-noise ratio of phosphate data, and 12 transitions were averaged for VO2 measurements. Averaged transitions were fit with a monoexponential curve for determination of the time constant (tau) of the responses. Mean tau values for on transients of PCr, P(i), and phrase 2 VO2 were 47.0, 57.7, and 44.5 s, respectively, whereas means tau values for off transients were 44.8, 42.1, and 33.4 s, respectively. There were no significant differences between tau values for phosphate- and VO2-measured transients or on and off transients. The similarity of on and off kinetics supports linear first-order respiratory control models. Measurement of phase 2 pulmonary VO2 kinetics to and from moderate-intensity small-muscle-mass exercise reflect muscle phosphate kinetics (and muscle oxygen consumption).
本研究的目的是直接比较磷酸肌酸（PCr）和无机磷（P(i)）的动态反应与在向中等强度运动过渡及从中等强度运动恢复过程中在肺部测量的摄氧量（VO2）的动态反应。在11名受试者（7名男性和4名女性；平均年龄27岁）向中等强度方波踝关节跖屈运动过渡及从中等强度方波踝关节跖屈运动恢复的过程中，通过31P-核磁共振波谱法测量PCr和P(i)的变化，通过质谱法逐次呼吸测量VO2的变化。为提高磷酸盐数据的信噪比，对三次重复过渡进行平均，为测量VO2，对12次过渡进行平均。将平均后的过渡拟合为单指数曲线，以确定反应的时间常数（tau）。PCr、P(i)和第二阶段VO2上升瞬变的平均tau值分别为47.0、57.7和44.5秒，而下降瞬变的平均tau值分别为44.8、42.1和33.4秒。磷酸盐测量瞬变和VO2测量瞬变之间以及上升和下降瞬变之间的tau值没有显著差异。上升和下降动力学的相似性支持线性一级呼吸控制模型。测量向中等强度小肌肉群运动过渡及从中等强度小肌肉群运动恢复过程中的第二阶段肺VO2动力学反映了肌肉磷酸盐动力学（以及肌肉耗氧量）。
