Casaburi R, Weissman M L, Huntsman D J, Whipp B J, Wasserman K
J Appl Physiol Respir Environ Exerc Physiol. 1979 Jun;46(6):1054-60. doi: 10.1152/jappl.1979.46.6.1054.
Following exercise onset, CO2 output (VCO2) and O2 uptake (VO2) increase exponentially, but with appreciably different time constants. To determine the sensitivity of the time courses of these variables to altered ventilatory kinetics, rhythmic exercise was induced abruptly in anesthetized dogs by bilateral stimulation of the peripheral ends of the cut sciatic and femoral nerves. This increased the metabolic rate by 83 +/- 25 (SD) %. The dogs were ventilated with a constant-volume pump, the frequency of which was changed exponentially from the start of the exercise up to the ventilation that returned arterial CO2 and O2 pressure (PCO2 and PO2) in the steady state to resting levels. The time constant (tau) of the increase in ventilation (VE) was varied among trials. VCO2, VO2, end-tidal PCO2 and PO2, and arterial PCO2 were measured breath by breath. tauVO2 was constant at approximately 18 s regardless of alterations in tauVE. In contrast, tauVCO2 was strongly dependent on tauVE, apparently due to the larger body stores for CO2; the transitions were isocapnic when tau VE was approximately 40 s. We conclude that ventilatory dynamics can markedly influence the dynamics of CO2 exchange during exercise, but has no appreciable effect on O2 uptake dynamics.
运动开始后，二氧化碳排出量（VCO₂）和氧气摄取量（VO₂）呈指数增加，但时间常数明显不同。为了确定这些变量的时间进程对通气动力学改变的敏感性，通过双侧刺激切断的坐骨神经和股神经的外周端，在麻醉的狗身上突然诱发节律性运动。这使代谢率提高了83±25（标准差）%。用恒容泵对狗进行通气，从运动开始到通气使动脉血二氧化碳和氧气压力（PCO₂和PO₂）在稳态下恢复到静息水平，通气频率呈指数变化。通气增加（VE）的时间常数（τ）在各试验中有所不同。逐次测量VCO₂、VO₂、呼气末PCO₂和PO₂以及动脉血PCO₂。无论τVE如何变化，τVO₂都恒定在约18秒。相反，τVCO₂强烈依赖于τVE，这显然是由于二氧化碳的体内储存量较大；当τVE约为40秒时，转变是等碳酸的。我们得出结论，通气动力学可显著影响运动期间二氧化碳交换的动力学，但对氧气摄取动力学无明显影响。
