The effect of He-O-2 exposure on metabolic rate, thermoregulation and thermal conductance during normothermia and daily torpor
The effect of He-O-2 exposure on metabolic rate, thermoregulation and thermal conductance during normothermia and daily torpor
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DOI：
10.1007/bf00263982
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发表时间：
1996-07-01
期刊：
影响因子：
--
通讯作者：
Kortner, G
中科院分区：
文献类型：
--
作者：
Geiser, F;Song, X;Kortner, G
最近，有人提出，在麻木的低代谢率可能更好地解释了热传导的减少，而不是体温下降或代谢抑制。我们测试了这一假设，同时测量体温和代谢率作为一个功能的环境温度在两个迟钝和正常体温的条纹面dunnarts，Sminthopsis macroura（Marsupialia;约。25 g体重），暴露于空气或He-O-2（氦气中含21%氧气）气氛中。He-O-2暴露增加的热传导的恒温哺乳动物的两倍，相比，没有明显的副作用的空气气氛。常温S. He-O-2使大尾两栖类的表观热导率增加了2倍，使其静息代谢率比空气中增加了2倍。托匹德湾在高于体温设定点的环境温度下暴露于He-O-2的macroura显示出完全不同的代谢反应。与正常体温的个体相比，尽管He-O-2中的表观热导率略有升高，但迟钝个体的代谢率显著降低或保持与空气中的代谢率相似。此外，代谢率在麻木的只是一小部分的正常体温的个人，虽然表观热导率只略有不同，正常体温和麻木。我们的研究表明，低导热性不是在休眠期间低代谢率的原因。这表明，在体温设定点以上的迟钝性内温动物的代谢率和体温之间的相互关系从根本上不同于正常体温和恒温内温动物。
Recently it was proposed that the low metabolic rate during torpor may be better explained by the reduction of thermal conductance than the drop of body temperature or metabolic inhibition. We tested this hypothesis by simultaneously measuring body temperature and metabolic rate as a function of ambient temperature in both torpid and normothermic stripe-faced dunnarts, Sminthopsis macroura (Marsupialia; approx. 25 g body mass), exposed to either air or He-O-2 (21% oxygen in helium) atmospheres. He-O-2 exposure increases the thermal conductance of homeothermic mammals by about twofold in comparison to an air atmosphere without apparent side-effects. Normothermic S. macroura exposed to He-O-2 increased resting metabolic rate by about twofold in comparison to that in air because of the twofold increase in apparent thermal conductance. Torpid S. macroura exposed to He-O-2 at ambient temperatures above the set-point for body temperature showed a completely different metabolic response. In contrast to normothermic individuals, torpid individuals significantly decreased or maintained a similar metabolic rate as those in air although the apparent thermal conductance in He-O-2 was slightly raised. Moreover, the metabolic rate during torpor was only a fraction of that of normothermic individuals although the apparent thermal conductance differed only marginally between normothermia and torpor. Our study shows that a low thermal conductance is not the reason for the low metabolic rates during torpor. It suggests that interrelations between metabolic rate and body temperature of torpid endotherms above the set-point for body temperature differ fundamentally from those of normothermic and homeothermic endotherms.