Song X, Körtner G, Geiser F
Department of Zoology, University of New England, Armidale, NSW, Australia.
J Comp Physiol B. 1995;165(4):291-7. doi: 10.1007/BF00367312.
Physiological mechanisms causing reduction of metabolic rate during torpor in heterothermic endotherms are controversial. The original view that metabolic rate is reduced below the basal metabolic rate because the lowered body temperature reduces tissue metabolism has been challenged by a recent hypothesis which claims that metabolic rate during torpor is actively downregulated and is a function of the differential between body temperature and ambient temperature, rather than body temperature per se. In the present study, both the steady-state metabolic rate and body temperature of torpid stripe-faced dunnarts, Sminthopsis macroura (Dasyuridae: Marsupialia), showed two clearly different phases in response to change of air temperature. At air temperatures between 14 and 30 degrees C, metabolic rate and body temperature decreased with air temperature, and metabolic rate showed an exponential relationship with body temperature (r2 = 0.74). The Q10 for metabolic rate was between 2 and 3 over the body temperature range of 16 to 32 degrees C. The difference between body temperature and air temperature over this temperature range did not change significantly, and the metabolic rate was not related to the difference between body temperature and air temperature (P = 0.35). However, the apparent conductance decreased with air temperature. At air temperatures below 14 degrees C, metabolic rate increased linearly with the decrease of air temperature (r2 = 0.58) and body temperature was maintained above 16 degrees C, largely independent of air temperature. Over this air temperature range, metabolic rate was positively correlated with the difference between body temperature and air temperature (r2 = 0.61). Nevertheless, the Q10 for metabolic rate between normothermic and torpid thermoregulating animals at the same air temperature was also in the range of 2-3.(ABSTRACT TRUNCATED AT 250 WORDS)
变温性恒温动物在蛰伏期间导致代谢率降低的生理机制存在争议。最初的观点认为，代谢率降低至基础代谢率以下是因为体温降低导致组织代谢减少，但最近的一个假说对这一观点提出了挑战。该假说认为，蛰伏期间的代谢率是被主动下调的，并且是体温与环境温度之差的函数，而非体温本身。在本研究中，蛰伏状态的带纹袋鼬（Sminthopsis macroura，袋鼬科：有袋目）的稳态代谢率和体温在响应气温变化时呈现出两个明显不同的阶段。在14至30摄氏度的气温下，代谢率和体温随气温下降，且代谢率与体温呈指数关系（r2 = 0.74）。在16至32摄氏度的体温范围内，代谢率的Q10在2至3之间。在此温度范围内，体温与气温之差没有显著变化，且代谢率与体温和气温之差无关（P = 0.35）。然而，表观传导率随气温下降。在气温低于14摄氏度时，代谢率随气温下降呈线性增加（r2 = 0.58），且体温维持在16摄氏度以上，很大程度上独立于气温。在此气温范围内，代谢率与体温和气温之差呈正相关（r2 = 0.61）。尽管如此，在相同气温下，正常体温和蛰伏体温调节动物之间代谢率的Q10也在2 - 3范围内。（摘要截选至250字）
