Maximum metabolism and thermoregulation in laboratory mice

Abstract

Resting metabolism rate (RMR) was measured in adult white mice\rat various temperatures ranging from 32 to — 10°C. At 0°C and 20°C\rthe RMR measurements in normal air were followed by measurements\rwhere a mixture of 80% He and 20% Oj was used to induce maximum\r.thermogenesis. The maximum metabolism in He-O, (8.3 ccmCVgXhr)\rwas observed at 20°C, while in normal air the highest values (7.9 ccm\rOz/gXhr) were noted at 10 and 5°C. The high level of metabolism was\rmaintained only by 5 to 15 minutes. Constant rectal body temperature\rwas maintained only within rage of ambients between 32 and 10°C. At\r— 10°C the body temperature dropped to its lowest value (20.4°C).