Mortola J P, Lanthier C
Department of Physiology, McGill University, Montreal, Quebec, Canada.
Respir Physiol. 1996 Mar;103(3):263-70. doi: 10.1016/0034-5687(95)00093-3.
Conscious newborns of 12 species from 4 mammalian orders, ranging in body mass (M) from 1 g (mouse) to 5 kg (deer), were studied during air and during 5% CO2 breathing. The interspecies relationship between oxygen consumption (VO2) and M was the same in air and hypercapnia, in both cases VO2 alpha M 0.90; on average, hypercapnic VO2 was 101% of the air value. In 5% CO2, ventilation (VE) increased in all newborns, mostly because of the increase in tidal volume (178%), whereas breathing rates averaged 98% of the air values. The hyperpnea during CO2 was slightly greater in the larger newborns. Body temperature was not altered by CO2 breathing. We conclude that the average respiratory response of the newborn to moderate hypercapnia is a hyperventilation different from that of the neonatal mammal in acute hypoxia (Mortola et al., Respir. Physiol. 78: 31-43, 1989). In fact, hypercapnic hyperventilation resulted only from the hyperpnea, with no hypometabolic contribution, and the hyperpnea reflected the increase in tidal volume, with no change in rate. It is also concluded that the neonatal hypometabolic response is specific to hypoxia, and not an undifferentiated response to chemoreceptors stimulation.
对来自4个哺乳动物目12个物种的清醒新生动物进行了研究，其体重（M）范围从1克（小鼠）到5千克（鹿），研究在空气中以及在吸入5%二氧化碳时进行。在空气中和高碳酸血症时，氧耗量（VO2）与体重之间的种间关系相同，两种情况下VO2αM 0.90；平均而言，高碳酸血症时的VO2是空气中值的101%。在5%二氧化碳环境中，所有新生动物的通气量（VE）均增加，主要是因为潮气量增加（178%），而呼吸频率平均为空气中值的98%。较大的新生动物在二氧化碳环境中的呼吸急促略更明显。二氧化碳呼吸未改变体温。我们得出结论，新生动物对中度高碳酸血症的平均呼吸反应是一种与急性缺氧时新生哺乳动物不同的通气过度（莫托拉等人，《呼吸生理学》78: 31 - 43, 1989）。事实上，高碳酸血症性通气过度仅由呼吸急促导致，没有低代谢的作用，且呼吸急促反映了潮气量的增加，频率没有变化。还得出结论，新生动物的低代谢反应是缺氧特有的，而非对化学感受器刺激的无差别反应。
