Meeting Abstract
Deer mice (Peromyscus maniculatus) forage over long distances in habitats characterized by extreme temperatures, hypoxia, and low primary productivity. The goal of this study was to quantify locomotion costs at different speeds (20, 25, and 30 m/min), temperatures (10 or 21°C), and inclines (0° or +25°). Using a Sable Systems respirometry treadmill we measured VO2 and VCO2 in mice [n=12 f, n=8 m] A) 10 minutes before exercise, B) while running for four minutes at each increasing speed, and C) a 15-min recovery period. During each trial mice ran 260 meters in distance and with the 25°-incline they vertically climbed 120 meters. Mice showed a transient (~2 minute) increase in VO2 (and RER) during the onset of exercise. At 21°C the VO2 remained constant with increasing velocity. Interestingly, the VO2 of 10°C mice running at both 0° or 25° inclines decreased with running speed, and by the end did not differ from those running at 21°C. Incline had a negligible effect on VO2. Mice running at 10°C at 30 m/min at a 25° incline did not differ from those measured in the same mice during the first five minutes of rest, suggesting the mice used locomotor muscle activity to offset thermoregulatory energy expenditure.
