Response time and sensitivity of the ventilatory response to CO2 in unanesthetized intact dogs: central vs. peripheral chemoreceptors.
Response time and sensitivity of the ventilatory response to CO2 in unanesthetized intact dogs: central vs. peripheral chemoreceptors.
复制标题
DOI：
10.1152/japplphysiol.00926.2005
复制
发表时间：
2006
影响因子：
3.3
通讯作者：
Curtis A. Smith;J. Rodman;B. Chenuel;K. Henderson;J. Dempsey
中科院分区：
文献类型：
--
作者：
Curtis A. Smith;J. Rodman;B. Chenuel;K. Henderson;J. Dempsey
我们评估了完整、未麻醉的狗对肺泡P(CO2)方波变化的呼吸反应的速度，以及中央化学感受器与颈动脉体化学感受器对CO2的稳态呼吸反应的相对增益。我们通过体外灌流可逆性分离的颈动脉窦来维持颈动脉体体化学感受器的正常紧张性活动，同时防止它感知到二氧化碳的全身性变化，从而使我们能够单独确定中央化学感受器的反应。我们发现了以下内容。1)仅中枢化学感受器的呼吸反应比颈动脉小体感觉到二氧化碳变化慢11.2(SD=3.6)S。2)平均而言，中枢化学感受器对二氧化碳稳态增加的贡献约为63%。中枢化学感受器和颈动脉体部化学感受器的相对贡献在犬与犬之间存在广泛的变异性；6只狗中有4只的中枢化学感受器超过颈动脉体增重，但有2只狗的颈动脉体增重超过中央二氧化碳增重。如果人类对狗的反应类似，我们认为中枢化学感受器对颈动脉化学感受器的反应较慢，阻止了中央化学感受器对动脉P(CO2)快速、瞬时变化的呼吸机反应做出显著贡献，例如在睡眠障碍呼吸期间观察到的低通气期或过度通气期后的那些变化。然而，中枢化学感受器对稳态高碳酸血症的较大平均反应性表明，一旦不稳定/周期性呼吸完全建立，这些受体可能对呼吸过量有显著贡献。
We assessed the speed of the ventilatory response to square-wave changes in alveolar P(CO2) and the relative gains of the steady-state ventilatory response to CO2 of the central chemoreceptors vs. the carotid body chemoreceptors in intact, unanesthetized dogs. We used extracorporeal perfusion of the reversibly isolated carotid sinus to maintain normal tonic activity of the carotid body chemoreceptor while preventing it from sensing systemic changes in CO2, thereby allowing us to determine the response of the central chemoreceptors alone. We found the following. 1) The ventilatory response of the central chemoreceptors alone is 11.2 (SD = 3.6) s slower than when carotid bodies are allowed to sense CO2 changes. 2) On average, the central chemoreceptors contribute approximately 63% of the gain to steady-state increases in CO2. There was wide dog-to-dog variability in the relative contributions of central vs. carotid body chemoreceptors; the central exceeded the carotid body gain in four of six dogs, but in two dogs carotid body gain exceeded central CO2 gain. If humans respond similarly to dogs, we propose that the slower response of the central chemoreceptors vs. the carotid chemoreceptors prevents the central chemoreceptors from contributing significantly to ventilatory responses to rapid, transient changes in arterial P(CO2) such as those after periods of hypoventilation or hyperventilation ("ventilatory undershoots or overshoots") observed during sleep-disordered breathing. However, the greater average responsiveness of the central chemoreceptors to brain hypercapnia in the steady-state suggests that these receptors may contribute significantly to ventilatory overshoots once unstable/periodic breathing is fully established.