Pandit J J, Robbins P A
University Laboratory of Physiology, Oxford, UK.
Respiration. 1997;64(1):86-95. doi: 10.1159/000196649.
The purpose of this study was to examine whether sustained hypoxia during exercise attenuates the degree of decline in hypoxic ventilatory sensitivity which occurs during sustained hypoxia at rest. The acute ventilatory response to hypoxia (AHVR) was used as a measure of the hypoxic ventilatory chemoreflex sensitivity. Seven subjects undertook three protocols. Protocol A was designed to assess the reduction in AHVR as a result of 20 min of isocapnic hypoxia (end-tidal PO2 50 mm Hg) at rest. The first AHVR (control) was measured on exposure to the hypoxia, and the second AHVR (test) measured 6 min after the end of the hypoxic period. Protocols B and C were designed to assess the reduction in AHVR as a result of 20 min of isocapnic hypoxic exercise (70 W). In protocol B, the AHVR (test) was measured at rest, 6 min after the end of 20 min of isocapnic hypoxic (end-tidal PO2 55 mm Hg) exercise. In protocol C, the AHVR (control) as measured at rest, 6 min after the end of 20 min of euoxic (end-tidal PO2 100 mm Hg) isocapnic exercise. There was a 30 +/- 5% decline (mean +/- SEM) in the magnitude of the AHVR after the period of sustained hypoxia at rest. There was an 11 +/- 7% decline in the magnitude of the resting AHVR after the period of sustained hypoxic exercise. The percentage change in AHVR following hypoxic exercise was significantly less than following hypoxia at rest (p < 0.05; paired t test). We conclude that the decline in hypoxic chemoreflex sensitivity which occurs during sustained hypoxia at rest is genuinely attenuated as a result of exercise.
本研究的目的是检验运动期间的持续性低氧是否会减弱静息时持续性低氧过程中出现的低氧通气敏感性下降程度。急性低氧通气反应（AHVR）被用作低氧通气化学反射敏感性的一项指标。7名受试者进行了三项实验方案。方案A旨在评估静息时20分钟等碳酸低氧（呼气末PO2 50 mmHg）导致的AHVR降低情况。首次AHVR（对照）在低氧暴露时测量，第二次AHVR（测试）在低氧期结束后6分钟测量。方案B和C旨在评估20分钟等碳酸低氧运动（70 W）导致的AHVR降低情况。在方案B中，AHVR（测试）在静息时测量，即在20分钟等碳酸低氧（呼气末PO2 55 mmHg）运动结束后6分钟测量。在方案C中，AHVR（对照）在静息时测量，即在20分钟常氧（呼气末PO2 100 mmHg）等碳酸运动结束后6分钟测量。静息时持续性低氧期后，AHVR幅度下降了30±5%（平均值±标准误）。持续性低氧运动期后，静息AHVR幅度下降了11±7%。低氧运动后AHVR的百分比变化显著小于静息低氧后的变化（p<0.05；配对t检验）。我们得出结论，静息时持续性低氧过程中出现的低氧化学反射敏感性下降确实会因运动而减弱。
