OXYGEN SUPPLY AND PERFORMANCE IN PEROMYSCUS: METABOLIC AND CIRCULATORY RESPONSES TO EXERCISE

Abstract

Adult mice, Peromyscus leucopus novaboracensis, were exercised on a treadmill at various running speeds up to the highest obtainable at levels of oxygen ranging from 60 to 196 mm Hg. Oxygen consumption was not directly proportional to work rate as found in man and dog, and declined with a fall in the partial pressure of oxygen [Formula: see text] at the same work rate. As noted in other species, dependence of oxygen consumption on oxygen supply in Peromyscus varied with the level of exertion. The uptake at the highest speed was reduced by a relatively small fall in [Formula: see text] below normal air pressure whereas the uptake in resting mice was relatively insensitive to a reduction in [Formula: see text]. Heart rates varied in proportion to running speed and to oxygen consumption and were increased by a fall in [Formula: see text] at the same running speed.