Feist D D, Rosenmann M
Can J Physiol Pharmacol. 1976 Apr;54(2):146-53. doi: 10.1139/y76-023.
The calorigenic response (millilitres O2 per gram pre hour) to injected norepinephrine (NE) was compared as an index of nonshivering thermogenesis (NST) in the following groups of the Alaska red-backed vole (Clethrionomys rutilus): (1) summer, (2) fall acclimatized, (3) winter acclimatized, (4) 20 degrees C acclimated and (5) 5 degrees C acclimated. The metabolic response was tested at thermoneutrality (25 degrees C) and during cold exposure (5 degrees C). Winter acclimatized voles showed a significantly greater metabolic response to NE than summer voles at both 25 degrees C and 5 degrees C. In summer or winter voles the total metabolic rate after NE (Mne) was similar at 25 degrees C and 5 degrees C but the fraction of the total caused by exogenous NE was lower at 5 degrees C. Thus, thermogenesis during cold exposure and resulting from exogenous NE appear to be based on the same mechanism, and NE has thermoregulatory significance in these voles. The magnitude of the NE response in winter voles was comparable to he highest values reported for bats and exceeded levels reported for other adult small mammal species. Summer acclimatized voles and those acclimatized to 20 degrees C in the laboratory were comparable in their response to NE but winter acclimatized voles were significantly more sensitive to NE than voles acclimated to 5 degrees C. The seasonal winter peak in MNE coincided with peaks previously found for maximum metabolic capacity (MMAX), maximum brown fat, and the period of coldest temperature in December-January. the ratio of MNE to Mmax was similar throughout the year. The results suggest that small arctic-subarctic rodents have a greater capacity for NE stimulated NST than rodents from temperate latitudes probably because they are acclimatized to colder seasonal condtions.
在阿拉斯加红背田鼠（Clethrionomys rutilus）的以下几组中，比较了注射去甲肾上腺素（NE）后的产热反应（每克每小时耗氧量毫升数），以此作为非颤抖性产热（NST）的指标：（1）夏季组，（2）秋季驯化组，（3）冬季驯化组，（4）20摄氏度驯化组和（5）5摄氏度驯化组。在热中性条件（25摄氏度）和冷暴露期间（5摄氏度）测试了代谢反应。在25摄氏度和5摄氏度时，冬季驯化的田鼠对NE的代谢反应均显著大于夏季田鼠。在夏季或冬季田鼠中，NE注射后的总代谢率（Mne）在25摄氏度和5摄氏度时相似，但外源性NE引起的总代谢率比例在5摄氏度时较低。因此，冷暴露期间由外源性NE引起的产热似乎基于相同的机制，并且NE在这些田鼠中具有体温调节意义。冬季田鼠对NE反应的幅度与蝙蝠报道的最高值相当，且超过了其他成年小型哺乳动物物种报道的水平。夏季驯化的田鼠和在实验室中驯化至20摄氏度的田鼠对NE的反应相当，但冬季驯化的田鼠对NE的敏感性显著高于驯化至5摄氏度的田鼠。MNE的季节性冬季峰值与先前发现的最大代谢能力（MMAX）、最大棕色脂肪以及12月至1月最冷温度期的峰值一致。全年MNE与Mmax的比值相似。结果表明，北极 - 亚北极小型啮齿动物比温带纬度的啮齿动物具有更大的NE刺激NST能力，这可能是因为它们适应了更寒冷的季节条件。
