Effect of ambient temperature on cardiovascular parameters in rats and mice: a comparative approach

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2004-08, Vol.287 (2), p.R391-R396
• Main Authors: Swoap, Steven J, Overton, J. Michael, Garber, Graham
• Format: Article
• Language: English
• Subjects: Animals; Blood Pressure - physiology; Consciousness; Female; Heart Rate - physiology; Mice; Motor Activity; Rats; Rats, Sprague-Dawley; Species Specificity; Telemetry; Temperature
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.00731.2003

1 Department of Biology, Williams College, Williamstown, Massachusetts 01267; and 2 Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, Florida 32306 Submitted 29 December 2003 ; accepted in final form 8 April 2004 Ambient air temperatures (T a ) of 29°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°C and incrementally decreasing by 4°C at each time interval to 18°C and then incrementally increasing back up to 30°C. As T a decreased, mean blood pressure, heart rate, and pulse pressure increased significantly for both mice (1.6 mmHg/°C, 14.4 beats·min –1 ·°C –1 , and 0.8 mmHg/°C, respectively) and rats (1.2 mmHg/°C, 8.1 beats·min –1 ·°C –1 , and 0.8 mmHg/°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. blood pressure; heart rate; standard deviation of the interbeat interval; radiotelemetry Address for reprint requests and other correspondence: S. J. Swoap, Dept. of Biology, Williams College, Williamstown, MA 01267 (E-mail: sswoap{at}williams.edu ).