Song X, Körtner G, Geiser F
University of New England, Armidale, New South Wales, Australia.
Am J Physiol. 1997 Dec;273(6):R2097-104. doi: 10.1152/ajpregu.1997.273.6.R2097.
We tested whether the reduction of metabolic rate (MR) in hibernating Cercartetus nanus (Marsupialia, 36 g) is better explained by the reduction of body temperature (Tb), the differential (delta T) between Tb and air temperature (Ta), or thermal conductance (C). Above the critical Ta during torpor (Ttc) of 4.8 +/- 0.7 degrees C where the Tb was not regulated, the steady-state MR was an exponential function of Tb (r2 = 0.92), and the overall Q10 was 3.3. However, larger Q10 values were observed at high Tb values during torpor, particularly within the thermoneutral zone (Q10 = 9.5), whereas low Q10 values were observed below Tb 20 degrees C (Q10 = 1.9). The delta T did not change over Ta 5-20 degrees C, although MR fell, and therefore the two variables were not correlated. Below the Ttc, Tb was regulated at 6.1 +/- 1.0 degrees C and MR increased proportionally to delta T. Our study suggests that MR in torpid C. nanus is largely determined by temperature effects and metabolic inhibition. In contrast, delta T explains MR only below the Ttc and C appears to affect MR only indirectly via changes of Tb, suggesting that delta T and C play only a secondary role in MR reduction during hibernation.
我们测试了以下哪种情况能更好地解释冬眠的南纹袋貂（有袋目，体重36克）代谢率（MR）的降低：体温（Tb）的降低、Tb与气温（Ta）之间的差值（δT），还是热传导率（C）。在蛰伏期临界Ta（Ttc）4.8±0.7摄氏度以上，此时Tb不受调节，稳态MR是Tb的指数函数（r2 = 0.92），总体Q10为3.3。然而，在蛰伏期Tb较高时，尤其是在热中性区内观察到较大的Q10值（Q10 = 9.5），而在Tb低于20摄氏度时观察到较低的Q10值（Q10 = 1.9）。尽管MR下降，但在Ta 5 - 20摄氏度范围内δT没有变化，因此这两个变量不相关。在Ttc以下，Tb被调节在6.1±1.0摄氏度，且MR与δT成比例增加。我们的研究表明，蛰伏的南纹袋貂的MR在很大程度上由温度效应和代谢抑制决定。相比之下，δT仅在Ttc以下解释MR，而C似乎仅通过Tb的变化间接影响MR，这表明δT和C在冬眠期间MR降低中仅起次要作用。
