Hallam J F, Dawson T J
School of Biological Science, University of New South Wales, Kensington, Australia.
Respir Physiol. 1993 Sep;93(3):305-14. doi: 10.1016/0034-5687(93)90076-m.
Previous studies have indicated that the pattern of respiration in marsupial and placental mammals may be different. Some marsupials have larger tidal volumes and slower respiratory rates under basal conditions. This study examined the respiratory responses of a small marsupial, Dasyuroides byrnei, to increasing metabolic demand. The highest metabolic rate elicited by cold exposure in a helium-oxygen atmosphere was 10.4 times the basal metabolic rate. Basal tidal volumes and respiratory rates were 138% and 46% respectively of the values predicted for placental mammals. The increasing oxygen demands of metabolism were met by increases in ventilation rather than by changes in oxygen extraction. Initially, tidal volume increased until it reached a maximum value 2.6 times that of basal tidal volume. Subsequently, ventilation was augmented by an increase in respiratory frequency. Ventilatory accommodation to an increasing oxygen demand indicated that D. byrnei has an excellent respiratory capacity to deal with the thermogenic demands of a cold environment.
先前的研究表明，有袋类哺乳动物和有胎盘类哺乳动物的呼吸模式可能有所不同。一些有袋类动物在基础条件下具有更大的潮气量和更低的呼吸频率。本研究考察了一种小型有袋动物——拜氏袋鼬（Dasyuroides byrnei）对代谢需求增加的呼吸反应。在氦氧环境中，冷暴露引发的最高代谢率是基础代谢率的10.4倍。基础潮气量和呼吸频率分别是有胎盘类哺乳动物预测值的138%和46%。代谢过程中不断增加的氧气需求是通过通气量的增加而非氧摄取的变化来满足的。起初，潮气量增加，直至达到基础潮气量2.6倍的最大值。随后，呼吸频率增加使通气量增大。对不断增加的氧气需求的通气调节表明，拜氏袋鼬具有出色的呼吸能力来应对寒冷环境产生热量的需求。
