Carroll J L, Bureau M A
Department of Pediatrics, McGill University, Montreal Children's Hospital, Canada.
Respir Physiol. 1988 Sep;73(3):339-49. doi: 10.1016/0034-5687(88)90055-2.
We studied the interaction of O2 and CO2 at the peripheral chemoreceptors in 6 two-week-old awake lambs. The method used, which selectively tested the peripheral chemoreceptors, measured the immediate ventilatory (VE) response to pure O2 and then to O2 + CO2. From room air, the animal was switched abruptly to either pure O2 or O2 + 5% CO2, O2 + 7.5% CO2, or O2 + 10% CO2. VE was measured before and 8-10 sec after a step change in the inspired gas. In response to pure O2, VE/kg dropped 131 +/- 30 ml/min.kg (38%). Repeat O2 tests performed with the addition of CO2 showed that CO2 interacted to blunt the response to pure O2; the VE change from pre-test baseline to 8-10 sec being -77 +/- 42, -18 +/- 25, and +8.5 +/- 60 for 5%, 7.5%, and 10% added CO2 respectively. Carotid body denervation eliminated the immediate VE responses to O2 and CO2. We conclude that in the 2-week-old awake lamb, (1) hyperoxia suppresses the O2 drive output of the peripheral chemoreceptors, (2) during hyperoxia O2 and CO2 still interact at the chemoreceptor level, and (3) despite hyperoxia, the peripheral chemoreceptors retain a substantial graded response to incremental transient CO2 challenge.
我们研究了6只两周大清醒羔羊外周化学感受器处氧气（O₂）和二氧化碳（CO₂）的相互作用。所采用的方法选择性地测试外周化学感受器，测量对纯氧然后对氧气加二氧化碳的即时通气（VE）反应。从室内空气开始，动物被突然切换至纯氧或氧气加5%二氧化碳、氧气加7.5%二氧化碳或氧气加10%二氧化碳。在吸入气体发生阶跃变化之前和之后8 - 10秒测量VE。对纯氧的反应中，VE/体重下降了131±30毫升/分钟·千克（38%）。添加二氧化碳后重复进行的氧气测试表明，二氧化碳相互作用减弱了对纯氧的反应；对于添加5%、7.5%和10%二氧化碳的情况，从测试前基线到8 - 10秒的VE变化分别为-77±42、-18±25和+8.5±60。颈动脉体去神经支配消除了对氧气和二氧化碳的即时VE反应。我们得出结论，在两周大的清醒羔羊中，（1）高氧抑制外周化学感受器的氧驱动输出，（2）在高氧期间氧气和二氧化碳仍在化学感受器水平相互作用，（3）尽管处于高氧状态，外周化学感受器对递增的短暂二氧化碳刺激仍保留显著的分级反应。
