Jochmans-Lemoine Alexandra, Villalpando Gabriella, Gonzales Marcelino, Valverde Ibana, Soria Rudy, Joseph Vincent
Centre de Recherche du CHU de Québec, and Université Laval, Quebec, Quebec, Canada G1L3L5.
Instituto Boliviano de Biologia de Altura, and Universidad Mayor de San Andrés, La Paz, Bolivia.
J Exp Biol. 2015 Apr;218(Pt 7):1035-43. doi: 10.1242/jeb.112862. Epub 2015 Feb 5.
Ecological studies show that mice can be found at high altitude (HA - up to 4000 m) while rats are absent at these altitudes, and there are no data to explain this discrepancy. We used adult laboratory rats and mice that have been raised for more than 30 generations in La Paz, Bolivia (3600 m), and compared their hematocrit levels, right ventricular hypertrophy (index of pulmonary hypertension) and alveolar surface area in the lungs. We also used whole-body plethysmography, indirect calorimetry and pulse oxymetry to measure ventilation, metabolic rate (O2 consumption and CO2 production), heart rate and pulse oxymetry oxygen saturation (pO2 ,sat) under ambient conditions, and in response to exposure to sea level PO2 (32% O2=160 mmHg for 10 min) and hypoxia (18% and 15% O2=90 and 75 mmHg for 10 min each). The variables used for comparisons between species were corrected for body mass using standard allometric equations, and are termed mass-corrected variables. Under baseline, compared with rats, adult mice had similar levels of pO2 ,sat, but lower hematocrit and hemoglobin levels, reduced right ventricular hypertrophy and higher mass-corrected alveolar surface area, tidal volume and metabolic rate. In response to sea level PO2 and hypoxia, mice and rats had similar changes of ventilation, but metabolic rate decreased much more in hypoxia in mice, while pO2 ,sat remained higher in mice. We conclude that laboratory mice and rats that have been raised at HA for >30 generations have different physiological responses to altitude. These differences might explain the different altitude distribution observed in wild rats and mice.
生态学研究表明，在高海拔地区（高达4000米）能发现小鼠，而大鼠在这些海拔高度不存在，且尚无数据解释这种差异。我们使用了在玻利维亚拉巴斯（海拔3600米）饲养了30多代的成年实验大鼠和小鼠，比较了它们的血细胞比容水平、右心室肥大（肺动脉高压指标）和肺内肺泡表面积。我们还使用全身体积描记法、间接量热法和脉搏血氧饱和度测定法，在环境条件下以及在暴露于海平面氧分压（32%氧气=160毫米汞柱，持续10分钟）和低氧（18%和15%氧气=90和75毫米汞柱，各持续10分钟）时，测量通气、代谢率（氧气消耗和二氧化碳产生）、心率和脉搏血氧饱和度（pO2，饱和度）。用于物种间比较的变量使用标准异速生长方程进行体重校正，称为体重校正变量。在基线状态下，与大鼠相比，成年小鼠的pO2、饱和度水平相似，但血细胞比容和血红蛋白水平较低，右心室肥大减轻，体重校正后的肺泡表面积、潮气量和代谢率较高。在暴露于海平面氧分压和低氧时，小鼠和大鼠的通气变化相似，但小鼠在低氧时代谢率下降幅度更大，而小鼠的pO2、饱和度仍较高。我们得出结论，在高海拔地区饲养超过30代的实验小鼠和大鼠对海拔有不同的生理反应。这些差异可能解释了在野生大鼠和小鼠中观察到的不同海拔分布情况。
