Central Limits to Sustainable Metabolic Rate Have No Role in Cold Acclimation of the Short-Tailed Field Vole (Microtus agrestis)
Central Limits to Sustainable Metabolic Rate Have No Role in Cold Acclimation of the Short-Tailed Field Vole (Microtus agrestis)
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DOI：
10.1086/physzool.67.5.30163885
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发表时间：
1994-09
期刊：
影响因子：
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通讯作者：
Regina M. McDevitt;J. Speakman
中科院分区：
文献类型：
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作者：
Regina M. McDevitt;J. Speakman
我们调查了在何种程度上的变化，在基础代谢率（BMR），肠道形态，和食物摄入量（FI），通常发生在小型哺乳动物的冷驯化过程中可以解释的概念，食物介导的限制可持续的代谢能量消耗。成年短尾田鼠（Microtus agrestis）通过连续暴露于5° C而受到冷应激。暴露10，20，50，和100 d（n = 6在所有情况下）产生显着的变化，耗氧量（V ~ o2），质量，FI，和干重的各种形态参数相比，田鼠没有冷暴露（n = 8）。在10°、20°和25° C条件下，随着冷暴露时间的延长，Vto 2（mL · min）显著增加。冷暴露100 d后，各试验温度下V_（to_2）均增加50%以上。冷暴露10 d后，摄食量（g · d）显著增加106%，但没有随着暴露时间的增加而进一步增加。对照组的FI（J · h <$）与BMR（J · h <$）之比为1.2，冷暴露10 d后增加到2.7。此后的比例下降，100天后冷暴露FI：BMR是没有显着不同的控制水平。冷暴露田鼠的质量随暴露时间的延长而显著增加。以下形态参数的质量随着冷暴露持续时间的增加而增加;全身质量、胴体、骨骼、皮毛、皮下脂肪、肝脏、肾脏、肺和肩胛间棕色脂肪（BAT）。冷暴露时间与肌肉、大肠、心脏和大脑的质量之间没有显著关系。使用逐步多元回归分析，我们发现，在BMR的变化主要是联系在一起的骨骼质量的变化。然而，当从分析中删除骨骼质量作为自变量时，BAT，肌肉和肠道质量作为重要的预测因子进入，共同解释了BMR中55.5%的变化。虽然FI增加冷暴露期间，增加（106%）显然是不足以沉淀在肠道中的肥大反应。然而，BMR确实随着冷暴露时间的增加而增加，这可能与BAT质量的增加以及产热能力有关。我们不能支持这样的假设，即在冷驯化过程中通常发生在BMR，食物摄入量和肠道形态的变化是食物介导的可持续代谢率限制的结果。
We investigated the extent to which the changes in basal metabolic rate (BMR), gut morphology, and food intake (FI) that typically occur during cold acclimation in small mammals can be explained by the concept of alimentary-mediated limits to sustainable metabolic energy expenditure. Adult short-tailed field voles (Microtus agrestis) were cold stressed by continuous exposure to 5° C. Exposure for 10, 20, 50, and 100 d (n = 6 in all cases) produced significant changes in oxygen consumption (V̇o2), mass, FI, and the dry weight of a variety of morphological parameters when compared with voles that were not cold exposed (n = 8). At 10°, 20°, and 25° C, V̇o2 (mL · min⁻¹) increased significantly with the duration of cold exposure. After 100 d cold exposure, V̇o2 had increased by more than 50% at each test temperature. Food intake (g · d⁻¹) increased significantly by 106% after 10 d cold exposure but did not increase further with increased exposure time. The ratio of FI (J · h⁻¹) to BMR (J · h⁻¹) was 1.2 in controls and increased to 2.7 after 10 d cold exposure. Thereafter the ratio decreased, and after 100 d cold exposure FI:BMR was not significantly different from control levels. The mass of cold-exposed voles increased significantly with duration of exposure. Masses of the following morphological parameters increased with increasing duration of cold exposure; whole body mass, carcass, skeleton, pelage, subcutaneous fat, liver, kidney, lung, and interscapular brown fat (BAT). There was no significant relationship between duration of cold exposure and the masses of muscle, large intestine, heart, and brain. Using stepwise multiple regression analysis we showed that variation in BMR was linked mostly to changes in skeletal mass. However, when skeletal mass was removed as an independent variable from the analysis, BAT, muscle, and gut mass entered as significant predictors, together explaining 55.5% of the variation in BMR. Although FI increased during cold exposure, the increase (106%) was apparently insufficient to precipitate a hypertrophic response in the gut. Nevertheless BMR did increase as duration of cold exposure increased, probably linked to an increase in BAT mass and thus thermogenic capacity. We cannot support the hypothesis that the changes that typically occur in BMR, food intake, and gut morphology during cold acclimation are a consequence of alimentary-mediated limits to sustainable metabolic rate.