Metabolic rate and body temperature reduction during hibernation and daily torpor.

@article{Geiser2004MetabolicRA,
  title={Metabolic rate and body temperature reduction during hibernation and daily torpor.},
  author={Fritz Geiser},
  journal={Annual review of physiology},
  year={2004},
  volume={66},
  pages={
          239-74
        }
}
  • F. Geiser
  • Published 11 February 2004
  • Biology
  • Annual review of physiology
Although it is well established that during periods of torpor heterothermic mammals and birds can reduce metabolic rates (MR) substantially, the mechanisms causing the reduction of MR remain a controversial subject. The comparative analysis provided here suggests that MR reduction depends on patterns of torpor used, the state of torpor, and body mass. Daily heterotherms, which are species that enter daily torpor exclusively, appear to rely mostly on the fall of body temperature (Tb) for MR… 

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References

SHOWING 1-10 OF 183 REFERENCES
Perspectives on Metabolic Suppression during Mammalian Hibernation and Daily Torpor
TLDR
A different experimental approach is proposed which could allow direct comparison of minimum MR at the same Tb during hibernation and induced hypothermia and hopefully will resolve if active inhibition of MR is indeed a state-dependent characteristic of torpor and hibernation.
Reduction of metabolism during hibernation and daily torpor in mammals and birds: temperature effect or physiological inhibition?
  • F. Geiser
  • Biology
    Journal of Comparative Physiology B
  • 2004
TLDR
Findings show that the reduction in metabolism during torpor of daily heterotherms and large hibernators can be explained largely by temperature effects, whereas a metabolic inhibition in addition to temperature effects may be used by small hibernator to reduce energy expenditure during torpora.
Relationships between body temperature, thermal conductance,Q10 and energy metabolism during daily torpor and hibernation in rodents
TLDR
It is suggested that the changes inC' represent a suite of physiological adaptations that have played a central role in the evolution of torpor, enabling rodents to regulateTB aboveTB during periods of very low heat production.
THE TEMPORAL ORGANIZATION OF DAILY TORPOR AND HIBERNATION: CIRCADIAN AND CIRCANNUAL RHYTHMS
TLDR
It is reviewed whether circadian and circannual rhythms, important in the timing of biological events in active animals, also play an important role during torpor when Tb is reduced substantially and may even fall below 0°C, and there is little evidence it is significantly affected by low Tb.
Respiratory Exchange and Ventilation during Nocturnal Torpor in Hummingbirds
TLDR
It is concluded that a normal Q10 effect is sufficient to explain the metabolic rate of torpid hummingbirds and that transient CO₂ storage may occur during entrance into torpor but is not a prerequisite for entrance.
Hibernation versus Daily Torpor in Mammals and Birds: Physiological Variables and Classification of Torpor Patterns
TLDR
Comparisons of several physiological variables appear to justify a distinction between the two torpor patterns, but of all variables tested, only the frequency distributions of maximum torpor bout duration and the minimum V̇o2 showed a clear gap between daily heterotherms and hibernators.
Reduction of metabolic rate and thermoregulation during daily torpor
TLDR
Over the air temperature range in which body temperature of S. macroura was not metabolically defended, metabolic rate during daily torpor was largely a function of body temperature, and even in thermoregulating animals, the reduction of metabolic rate from normothermia to torpor at a given air temperature can also be explained by temperature effects.
The effect of He−O2 exposure on metabolic rate, thermoregulation and thermal conductance during normothermia and daily torpor
Recently it was proposed that the low metabolic rate during torpor may be better explained by the reduction of thermal conductance than the drop of body temperature or metabolic inhibition. We tested
Daily Torpor and Thermoregulation in the Small Dasyurid Marsupials
Torpor in endotherms has only been observed in small species, suggesting that body mass determines the occurrence of torpor. The present study investigates the influence of body mass on the
The effect of temperature on the pattern of torpor in a marsupial hibernator
TLDR
Investigation of how changes in air temperature affect the duration of torpor bouts, metabolic rate, body temperature and weight loss of the marsupial hibernator Burramys parvus found a change in climate would most likely increase winter mortality of this endangered species.
...
...