RELATIONSHIPS BETWEEN RESPIRATORY QUOTIENT AND METABOLIC-RATE DURING ENTRY TO AND AROUSAL FROM DAILY TORPOR IN DEER MICE (PEROMYSCUS-MANICULATUS)

Deer mice were used to examine the time course of changes in respiratory quotient (RQ), metabolic rate (MR), and body temperature (Tb) during daily torpor at an ambient temperature of 10°C. For several hours prior to daily torpor, RQ steadily declined from 0.92 to 0.74, indicating a shift in primary metabolic substrate from carbohydrate to fat, while MR and Tb remained constant at 4.23 ± 0.44 mL O2/g.h and 36.6° ± 0.9°C, respectively. Entrance to daily torpor involved a transitory decrease in RQ (0.74-0.63-0.73) that lasted <12 min. This was followed by a rapid drop in MR and Tb. Respiratory quotient remained stable during steady-state torpor (0.74 ± 0.02). Metabolic rate and Tb in daily torpor were 1.12 ± 0.35 mL O2/g.h and 21.6° ± 1.6°C, respectively. A transitory increase in RQ (0.76-0.96-0.76) was associated with arousal. -from Author