Muñoz-Garcia Agustí, Ben-Hamo Miriam, Pinshow Berry, Williams Joseph B, Korine Carmi
Mitrani Department of Desert Ecology, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, 84990 Midreshet Ben-Gurion, Israel.
Physiol Biochem Zool. 2012 Sep-Oct;85(5):516-25. doi: 10.1086/666989. Epub 2012 Aug 8.
Total evaporative water loss is the sum of respiratory water loss (RWL) and cutaneous water loss (CWL) and constitutes the main avenue of water loss in bats. Because bats fly and have large surface-to-volume ratios, they potentially have high rates of RWL and CWL. Most species of small insectivorous bats have the ability to reduce their body temperature (T(b)) at rest, which substantially reduces energy expenditure and water loss. We hypothesized that bats reduce evaporative water loss during bouts of deep hypothermia (torpor) by decreasing RWL and CWL. We measured T(b), RWL, CWL, and resting metabolic rate (RMR) in Kuhl's pipistrelle Pipistrellus kuhlii, a small insectivorous bat. In support of our hypothesis, we found that RWL decreased with decreasing RMR. We found that CWL was lower in torpid individuals than in normothermic bats; however, bats in deep torpor had similar or higher CWL than bats in shallow torpor, suggesting that they exert a less effective physiological control over CWL when in deep torpor. Because insectivorous bats spend most of their lives in torpor or hibernation, the regulation of CWL in different heterothermic states has relevant ecological and evolutionary consequences.
总蒸发失水量是呼吸失水量（RWL）和皮肤失水量（CWL）之和，是蝙蝠失水的主要途径。由于蝙蝠飞行且体表与体积之比大，它们潜在的呼吸失水量和皮肤失水量较高。大多数小型食虫蝙蝠物种在休息时能够降低体温（T(b)），这会大幅减少能量消耗和失水量。我们推测蝙蝠在深度低温期（蛰伏）通过降低呼吸失水量和皮肤失水量来减少蒸发失水量。我们测量了库氏伏翼（Pipistrellus kuhlii）这种小型食虫蝙蝠的体温（T(b)）、呼吸失水量、皮肤失水量和静息代谢率（RMR）。为支持我们的假设，我们发现呼吸失水量随静息代谢率降低而减少。我们发现蛰伏个体的皮肤失水量低于正常体温的蝙蝠；然而，深度蛰伏的蝙蝠比浅度蛰伏的蝙蝠具有相似或更高的皮肤失水量，这表明它们在深度蛰伏时对皮肤失水量的生理控制效果较差。由于食虫蝙蝠一生大部分时间处于蛰伏或冬眠状态，不同异温状态下皮肤失水量的调节具有相关的生态和进化意义。
