Hibernation in Black Bears: Independence of Metabolic Suppression from Body Temperature

@article{Tien2011HibernationIB,
  title={Hibernation in Black Bears: Independence of Metabolic Suppression from Body Temperature},
  author={{\O}ivind T{\o}ien and John E. Blake and Dale M. Edgar and Dennis A. Grahn and H. Craig Heller and Brian M. Barnes},
  journal={Science},
  year={2011},
  volume={331},
  pages={906 - 909}
}
Black bears hibernate for 5 to 7 months a year and, during this time, do not eat, drink, urinate, or defecate. [...] Key Result Heart rates were reduced from 55 to as few as 9 beats per minute, with profound sinus arrhythmia. After returning to normal body temperature and emerging from dens, bears maintained a reduced metabolic rate for up to 3 weeks. The pronounced reduction and delayed recovery of metabolic rate in hibernating bears suggest that the majority of metabolic suppression during hibernation is…Expand
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References

SHOWING 1-10 OF 34 REFERENCES
BODY SURFACE TEMPERATURE OF HIBERNATING BLACK BEARS MAY BE RELATED TO PERIODIC MUSCLE ACTIVITY
TLDR
It is suggested that bears engage in bouts of muscle activity during the winter denning period that may result in the retention of muscle strength without elevating their core body temperature and without arousing from torpor. Expand
Suppression of Metabolism during Hibernation in Ground Squirrels (Citellus lateralis)
TLDR
Data from 11 ground squirrels indicate that respiratory acidosis occurs during hibernation but that its role may be limited to suppression of thermoregulatory thermogenesis and not suppression of metabolism below basal levels. Expand
Physiology: Hibernation in a tropical primate
TLDR
These findings indicate that arousals are determined by maximum body temperatures and that hypometabolism in hibernating animals is not necessarily coupled to a low body temperature. Expand
Metabolic rate and body temperature reduction during hibernation and daily torpor.
  • F. Geiser
  • Biology, Medicine
  • Annual review of physiology
  • 2004
TLDR
The comparative analysis provided here suggests that MR reduction depends on patterns of torpor used, the state of tor porpor, and body mass, which in turn affects metabolic inhibition and energy conservation. Expand
Cardiac function adaptations in hibernating grizzly bears (Ursus arctos horribilis)
TLDR
It is proposed that changes in atrial chamber function constitute a major adaptation during hibernation which allows the myocardium to conserve energy, avoid chamber dilation and remain healthy during a period of extremely low heart rates. Expand
Freeze avoidance in a mammal: body temperatures below 0 degree C in an Arctic hibernator.
TLDR
Hibernating arctic ground squirrels were able to adopt and spontaneously arouse from core body temperatures as low as -2.9 degrees C without freezing and plasma sampled from animals with below 0 degree C body temperatures had normal solute concentrations and showed no evidence of containing antifreeze molecules. Expand
Reduction of metabolism during hibernation and daily torpor in mammals and birds: temperature effect or physiological inhibition?
  • F. Geiser
  • Biology, Medicine
  • 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. Expand
Body temperature patterns during hibernation in a free-living Alaska marmot (Marmota broweri)
TLDR
At least six animals emerged from the hibernaculum suggesting that communal hibernation may be a strategy to reduce metabolic costs while maintaining above-freezing Tb. Expand
CNS regulation of body temperature in euthermic and hibernating marmots (Marmota flaviventris).
TLDR
It is demonstrated that the hypothalamic regulator of Tb is active throughout hibernation and that there are progressive changes in its thermosensitivity. Expand
Effects of ambient temperature on metabolic rate, respiratory quotient, and torpor in an arctic hibernator.
  • C. Buck, B. Barnes
  • Biology, Medicine
  • American journal of physiology. Regulatory, integrative and comparative physiology
  • 2000
TLDR
This relationship supports the hypothesis that availability of nonlipid metabolic fuels limits torpor duration in hibernating mammals; for T(a) values >0 degrees C, hypotheses linked to body temperature are supported. Expand
...
1
2
3
4
...