Arias-Reyes Christian, Soliz Jorge, Joseph Vincent
Centre de Recherche de l'Institute Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, QC, Canada.
Front Physiol. 2021 Mar 12;12:647822. doi: 10.3389/fphys.2021.647822. eCollection 2021.
Phylogeographic studies showed that house mice () originated in the Himalayan region, while common rats ( and ) come from the lowlands of China and India. Accordingly, it has been proposed that its origins gave mice, but not rats, the ability to invade ecological niches at high altitudes (pre-adaptation). This proposal is strongly supported by the fact that house mice are distributed throughout the world, while common rats are practically absent above 2,500 m. Considering that the ability of mammals to colonize high-altitude environments (>2,500 m) is limited by their capability to tolerate reduced oxygen availability, in this work, we hypothesize that divergences in the ventilatory, hematological, and metabolic phenotypes of mice and rats establish during the process of acclimatization to hypoxia (Hx). To test this hypothesis male FVB mice and Sprague-Dawley (SD) rats were exposed to Hx (12% O) for 0 h (normoxic controls), 6 h, 1, 7, and 21 days. We assessed changes in ventilatory [minute ventilation (V), respiratory frequency ( ), and tidal volume (V)], hematological (hematocrit and hemoglobin concentration), and metabolic [whole-body O consumption (VO) and CO production (VCO), and liver mitochondrial oxygen consumption rate (OCR) parameters]. Compared to rats, results in mice show increased ventilatory, metabolic, and mitochondrial response. In contrast, rats showed quicker and higher hematological response than mice and only minor ventilatory and metabolic adjustments. Our findings may explain, at least in part, why mice, but not rats, were able to colonize high-altitude habitats.
系统发育地理学研究表明，家鼠（）起源于喜马拉雅地区，而普通大鼠（和）则来自中国和印度的低地。因此，有人提出，其起源赋予了小鼠而非大鼠在高海拔地区侵入生态位的能力（预适应）。家鼠遍布全球，而普通大鼠在海拔2500米以上的地区几乎不存在，这一事实有力地支持了这一观点。考虑到哺乳动物在高海拔环境（>2500米）中定居的能力受到其耐受低氧能力的限制，在本研究中，我们假设小鼠和大鼠在适应低氧（Hx）的过程中，其通气、血液学和代谢表型会出现差异。为了验证这一假设，将雄性FVB小鼠和Sprague-Dawley（SD）大鼠暴露于低氧环境（12% O）中0小时（常氧对照组）、6小时、1天、7天和21天。我们评估了通气方面的变化[分钟通气量（V）、呼吸频率（）和潮气量（V）]、血液学方面的变化（血细胞比容和血红蛋白浓度）以及代谢方面的变化[全身氧气消耗量（VO）和二氧化碳产生量（VCO），以及肝脏线粒体氧气消耗率（OCR）参数]。与大鼠相比，小鼠的结果显示出通气、代谢和线粒体反应增强。相反，大鼠的血液学反应比小鼠更快、更高，而通气和代谢方面的调整较小。我们的研究结果至少可以部分解释为什么小鼠能够在高海拔栖息地定居，而大鼠却不能。
