Physiol Biochem Zool. 2022 May-Jun;95(3):239-250. doi: 10.1086/719932.
AbstractHibernation (i.e., seasonal or multiday torpor) has been described in mammals from five continents and represents an important adaptation for energy economy. However, direct quantifications of energy savings by hibernation are challenging because of the complexities of estimating energy expenditure in the field. Here, we applied quantitative magnetic resonance to determine body fat and body composition in hibernating (monito del monte). During an experimental period of 31 d in winter, fat was significantly reduced by g, and lean mass was significantly reduced by g. This fat and lean mass consumption is equivalent to a daily energy expenditure of hibernation (DEE) of kJ d, representing 13.4% of basal metabolic rate, with a proportional contribution of fat and lean mass consumption to DEE of 81% and 18%, respectively. During the deep heterothermic bouts of monitos, body temperature remained 0.41°C ± 0.2°C above ambient temperature, typical of hibernators. Animals shut down metabolism and passively cool down to a critical defended temperature of 5.0°C ± 0.1°C, where they begin thermoregulation in torpor. Using temperature data loggers, we obtained an empirical estimation of minimum thermal conductance of J g h °C, which is 107% of the expectation by allometric equations. With this, we parameterized body temperature/ambient temperature time series to calculate torpor parameters and metabolic rates in euthermia and torpor. Whereas the acute metabolic fall in each torpor episode is about 96%, the energy saved by hibernation is 88% (compared with the DEE of active animals), which coincides with values from the literature at similar body mass. Thus, estimating body composition provides a simple method to measure the energy saved by hibernation in mammals.
摘要 冬眠（即季节性或多日蛰伏）已在来自五个大洲的哺乳动物中被描述，代表了一种重要的节能适应。然而，由于在野外估算能量消耗的复杂性，直接量化冬眠的节能效果具有挑战性。在这里，我们应用定量磁共振来确定冬眠中的（monito del monte）的体脂肪和身体成分。在冬季的 31 天实验期间，脂肪显著减少了 g，瘦体重显著减少了 g。这种脂肪和瘦体重的消耗相当于冬眠的每日能量消耗（DEE）为 kJ d，占基础代谢率的 13.4%，脂肪和瘦体重消耗对 DEE 的比例贡献分别为 81%和 18%。在 monitos 的深度异温蛰伏期间，体温始终比环境温度高 0.41°C ± 0.2°C，这是冬眠动物的典型特征。动物停止新陈代谢并被动冷却到 5.0°C ± 0.1°C 的临界防御温度，在那里它们开始在蛰伏中进行体温调节。使用温度数据记录器，我们获得了经验估计的最小热导率为 J g h °C，这是通过体尺方程预测的 107%。利用这一点，我们对体温/环境温度时间序列进行参数化，以计算清醒和蛰伏时的蛰伏参数和代谢率。虽然每次蛰伏的急性代谢下降约为 96%，但冬眠节省的能量为 88%（与活跃动物的 DEE 相比），这与类似体重的文献值一致。因此，估计身体成分提供了一种简单的方法来测量哺乳动物冬眠节省的能量。
