Mark A. Chappell, Kimberly A. Hammond, Richard A. Cardullo, Gregory A. Russell, Enrico L. Rezende, Catherine Miller (2007). Deer mouse aerobic performance across altitudes: effects of developmental history and temperature acclimation. In press, Physiological and Biochemical Zoology.
ABSTRACT -- Aerobic physiology at high altitudes has been studied in many animals. Prior work on laboratory-bred deer mice (a species with a wide altitudinal range) showed depression of aerobic capacity at high altitude, even after acclimation. However, wild deer mice show no reduction in thermogenic performance at high altitude, and performance limits seem to be due to physiological and anatomical adjustments to environmental temperature and not to oxygen availability. We asked if across-altitude performance differences exist in deer mice after accounting for temperature acclimation (~ 5 °C and 20-25 °C) and prenatal and neonatal development altitude (340 m versus 3800 m). We measured maximal thermogenic oxygen consumption (VO2sum) in cold exposure and ran mice on a treadmill to elicit maximal exercise oxygen consumption (VO2max). We found a 10% reduction in VO2max at 3800 m from that at 340 m; thus the mice were able to compensate for most of the 37% reduction in oxygen availability at the higher altitude. Development altitude did not affect VO2max. There was no effect of test altitude or development altitude on VO2sum in warm-acclimated animals, but both test and development altitude strongly affected VO2sum in cold-acclimated mice, and compensation for hypoxia at 3800 m was considerably less than for exercise.