Bureau M A, Côté A, Blanchard P W, Hobbs S, Foulon P, Dalle D
J Appl Physiol (1985). 1986 Sep;61(3):836-42. doi: 10.1152/jappl.1986.61.3.836.
This study was undertaken to test the hypothesis that in the neonate the hypoxic chemoreflex drive adapts to steady-state hypoxia but not to progressive hypoxia. First we have compared the ventilatory (VE) response of 2-day-old conscious lambs to steady-state hypoxia with their response to progressive hypoxia. Second, we have quantified the chemoreceptor excitatory function operating at the end of each period of hypoxia by studying the immediate VE response to the withdrawal of the hypoxic stimulus. Lambs responded to steady-state hypoxia [fractional concentration of inspired O2 (FIO2) = 0.08] by a diphasic VE response but responded to progressive hypoxia (FIO2 0.21-0.08) by an exponential VE increase. Hyperventilation in steady-state hypoxia was transient; VE increased immediately from 532 to a mean peak response of 712 ml X kg-1 X min-1 and decreased to 595 ml X kg-1. min-1 within 10 min. With progressive hypoxia, VE increased within 13 min from 514 to 705 ml X kg-1 X min-1. At the end of steady-state and progressive hypoxia the abrupt withdrawal of the hypoxic drive caused an instantaneous VE decrease to 390 and 399 ml X kg-1 X min-1, respectively; the VE decrease was respectively 306 and 205 ml X kg-1 X min-1 (P less than 0.05). This demonstrates that during steady-state hypoxia the lambs had suffered a loss of one third of the chemoreceptor excitatory function.(ABSTRACT TRUNCATED AT 250 WORDS)
新生儿的低氧化学反射驱动可适应稳态低氧，但不能适应进行性低氧。首先，我们比较了2日龄清醒羔羊对稳态低氧和进行性低氧的通气（VE）反应。其次，通过研究低氧刺激撤除后立即出现的VE反应，我们量化了每个低氧期结束时起作用的化学感受器兴奋功能。羔羊对稳态低氧[吸入氧分数（FIO2）=0.08]的反应是双相VE反应，但对进行性低氧（FIO2 0.21-0.08）的反应是VE呈指数增加。稳态低氧时的过度通气是短暂的；VE立即从532增加到平均峰值反应712 ml·kg-1·min-1，并在10分钟内降至595 ml·kg-1·min-1。在进行性低氧时，VE在13分钟内从514增加到705 ml·kg-1·min-1。在稳态和进行性低氧结束时，低氧驱动的突然撤除分别导致VE立即降至390和399 ml·kg-1·min-1；VE下降分别为306和205 ml·kg-1·min-1（P<0.05）。这表明在稳态低氧期间，羔羊的化学感受器兴奋功能丧失了三分之一。（摘要截短于250字）
