Swoap Steven J, Overton J Michael, Garber Graham
Department of Biology, Williams College, Williamstown, MA 01267, USA.
Am J Physiol Regul Integr Comp Physiol. 2004 Aug;287(2):R391-6. doi: 10.1152/ajpregu.00731.2003. Epub 2004 Apr 15.
Ambient air temperatures (T(a)) of <6 degrees C or >29 degrees C have been shown to induce large changes in arterial blood pressure and heart rate in homeotherms. The present study was designed to investigate whether small incremental changes in T(a), such as those found in typical laboratory settings, would have an impact on blood pressure and other cardiovascular parameters in mice and rats. We predicted that small decreases in T(a) would impact the cardiovascular parameters of mice more than rats due to the increased thermogenic demands resulting from a greater surface area-to-volume ratio in mice relative to rats. Cardiovascular parameters were measured with radiotelemetry in mice and rats that were housed in temperature-controlled environments. The animals were exposed to different T(a) every 72 h, beginning at 30 degrees C and incrementally decreasing by 4 degrees C at each time interval to 18 degrees C and then incrementally increasing back up to 30 degrees C. As T(a) decreased, mean blood pressure, heart rate, and pulse pressure increased significantly for both mice (1.6 mmHg/ degrees C, 14.4 beats.min(-1). degrees C(-1), and 0.8 mmHg/ degrees C, respectively) and rats (1.2 mmHg/ degrees C, 8.1 beats.min(-1). degrees C(-1), and 0.8 mmHg/ degrees C, respectively). Thus small changes in T(a) significantly impact the cardiovascular parameters of both rats and mice, with mice demonstrating a greater sensitivity to these T(a) changes.
环境空气温度（T(a)）低于6摄氏度或高于29摄氏度已被证明会引起恒温动物动脉血压和心率的大幅变化。本研究旨在调查T(a)的微小增量变化，如在典型实验室环境中发现的变化，是否会对小鼠和大鼠的血压及其他心血管参数产生影响。我们预测，由于小鼠相对于大鼠具有更大的表面积与体积比，导致产热需求增加，T(a)的小幅下降对小鼠心血管参数的影响将大于大鼠。在温度可控环境中饲养的小鼠和大鼠，通过无线电遥测技术测量心血管参数。动物每隔72小时暴露于不同的T(a)，从30摄氏度开始，每次时间间隔以4摄氏度的幅度逐渐降至18摄氏度，然后再逐渐回升至30摄氏度。随着T(a)的降低，小鼠（分别为1.6 mmHg/摄氏度、14.4次/分钟·摄氏度和0.8 mmHg/摄氏度）和大鼠（分别为1.2 mmHg/摄氏度、8.1次/分钟·摄氏度和0.8 mmHg/摄氏度）的平均血压、心率和脉压均显著升高。因此，T(a)的微小变化会显著影响大鼠和小鼠的心血管参数，其中小鼠对这些T(a)变化表现出更高的敏感性。
