JENKINS, J.L.; BUCK, C.L.: Metabolic Rate Reduction During Entry into Torpor: A Consequence of Body Temperature Effects or Metabolic Suppression?

During hibernation, animals conserve endogenous fuels by entering torpor, a condition characterized by profound reduction of metabolism and body temperature. The mechanisms by which animals achieve and maintain extended periods of hypometabolism and hypothermia are unclear. Some investigators conclude that low metabolic rates are a consequence of low body temperature (i.e., Q₁₀ effects on metabolism) while others have demonstrated that hibernators can significantly reduce metabolism with only minimal decreases in body temperature (i.e., temperature-independent metabolic suppression). In order to differentiate among the potential mechanisms affording hypometabolism in 13-lined ground squirrels, we made simultaneous measures of body and brain temperature and metabolism during arousal and subsequent entry into torpor. Preliminary data suggest that the reduction in metabolism is a consequence of decreasing body temperature and temperature-independent inhibition of metabolism is not necessary for entry into torpor in this species.