The object of this study was to investigate the effect of central chemoreceptor stimulation on the ventilatory responses to peripheral chemoreceptor stimulation. 2. The level of central chemoreceptor stimulation was varied by performing experiments at two different levels of end-tidal CO2 pressure (PCO2). Variations in peripheral chemoreceptor stimulus were achieved by varying arterial pH (at constant end-tidal PCO2) and by varying end-tidal O2 pressure (PO2). 3. Two protocols were each performed on six human subjects. In one protocol ventilatory measurements were made during eucapnia, when the arterial pH was lowered from 7.4 to 7.3. The variation in pH was achieved by the progressive infusion of acid (0.1 M HCl). In the other protocol ventilatory measurements were made during hypercapnia, when the arterial pH was increased from 7.3 to 7.4. The variation in pH was achieved by the progressive infusion of 1.26% NaHCO3. In each protocol ventilatory responses were measured during euoxia (end-tidal PO2, 100 Torr), hypoxia (end-tidal PO2, 50 Torr) and hyperoxia (end-tidal PO2, 300 Torr), with end-tidal PCO2 held constant. 4. The increase in ventilatory sensitivity to arterial pH induced by hypoxia (50 Torr) was not significantly different between protocols (acid protocol, -104 +/- 31 l min-1 (pH unit)-1 vs. bicarbonate protocol, -60 +/- 44 l min-1 (pH unit)-1; mean +/- S.E.M.; not significant (n.s.)). The ventilatory sensitivity to hypoxia at an arterial pH of 7.35 was not significantly different between protocols (acid protocol, 14.7 +/- 3.3 l min-1 vs. bicarbonate protocol, 15.6 +/- 2.4 l min-1; mean +/- S.E.M.; n.s.). The results provide no evidence to suggest that peripheral chemoreflex ventilatory responses are modulated by central chemoreceptor stimulation.
摘要
本研究的目的是调查中枢化学感受器刺激对呼吸对外周化学感受器刺激反应的影响。2. 通过在两种不同的呼气末二氧化碳分压（PCO2）水平下进行实验来改变中枢化学感受器刺激的水平。通过改变动脉血pH值（在呼气末PCO2恒定的情况下）以及改变呼气末氧分压（PO2）来实现外周化学感受器刺激的变化。3. 对六名人类受试者分别进行了两种实验方案。在一种方案中，在动脉血pH值从7.4降至7.3的等碳酸血症期间进行通气测量。通过逐步输注酸（0.1 M HCl）来实现pH值的变化。在另一种方案中，在动脉血pH值从7.3升至7.4的高碳酸血症期间进行通气测量。通过逐步输注1.26% NaHCO3来实现pH值的变化。在每个方案中，在正常氧分压（呼气末PO2，100 Torr）、低氧（呼气末PO2，50 Torr）和高氧（呼气末PO2，300 Torr）期间测量通气反应，同时保持呼气末PCO2恒定。4. 低氧（50 Torr）引起的对动脉血pH值通气敏感性的增加在两种方案之间无显著差异（酸方案，-104±±±31 l min-1（pH单位）-1对比碳酸氢盐方案，-60±±±44 l min-1（pH单位）-1；平均值±±±标准误；无显著差异（n.s.））。在动脉血pH值为7.35时对低氧的通气敏感性在两种方案之间无显著差异（酸方案，14.7±±±3.3 l min-1对比碳酸氢盐方案，15.6±±±2.4 l min-1；平均值±±±标准误；n.s.）。结果没有提供证据表明外周化学感受性反射通气反应受中枢化学感受器刺激的调节。
