A comparison of temperature regulation in hibernating rodents

Lyman, Charles P.; O'Brien, RC

doi:10.1152/ajplegacy.1974.227.1.218

Cited by 23 publications

(2 citation statements)

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“…It is generally accepted that the ability for thermoregulation persists during that part of the hibernation process when T b reaches the set point of metabolic defense (16,17,19,22,24,36), and it seems reasonable that the physiological processes underlying thermoregulation at low T a values during hibernation, torpor, and normothermia are similar (14,20,32). At T a values above the T b set point, i.e., above the animal's preferred T b , there is no need for counteractive heat production.…”

Section: Hibernation Is a Voluntary And Well-regulated Adaptive Respomentioning

confidence: 99%

Regulation of body temperature and energy requirements of hibernating Alpine marmots (Marmota marmota)

Ortmann

Heldmaier

2000

American Journal of Physiology-Regulatory, Integrative and Comp

110

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Body temperature and metabolic rate were recorded continuously in two groups of marmots either exposed to seasonally decreasing ambient temperature (15 to 0 degrees C) over the entire hibernation season or to short-duration temperature changes during midwinter. Hibernation bouts were characterized by an initial 95% reduction of metabolic rate facilitating the drop in body temperature and by rhythmic fluctuations during continued hibernation. During midwinter, we observed a constant minimal metabolic rate of 13.6 ml O(2) x kg(-1) x h(-1) between 5 and 15 degrees C ambient temperature, although body temperature increased from 7.8 to 17.6 degrees C, and a proportional increase of metabolic rate below 5 degrees C ambient temperature. This apparent lack of a Q(10) effect shows that energy expenditure is actively downregulated and controlled at a minimum level despite changes in body temperature. However, thermal conductance stayed minimal (7.65 +/- 1.95 ml O(2) x kg(-1) x h(-1) x degrees C(-1)) at all temperatures, thus slowing down cooling velocity when entering hibernation. Basal metabolic rate of summer-active marmots was double that of winter-fasting marmots (370 vs. 190 ml O(2) x kg(-1) x h(-1)). In summary, we provide strong evidence that hibernation is not only a voluntary but a well-regulated strategy to counter food shortage and increased energy demands during winter.

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Section: Hibernation Is a Voluntary And Well-regulated Adaptive Respomentioning

confidence: 99%

Regulation of body temperature and energy requirements of hibernating Alpine marmots (Marmota marmota)

Ortmann

Heldmaier

2000

American Journal of Physiology-Regulatory, Integrative and Comp

110

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“…It is, however, becoming increasingly difficult to differentiate between certain responses owing to inadequate physiological definitions of certain terms (McKechnie & Lovegrove 2002). Whereas the phenotypic and genotypic characteristics of hibernation and torpor are well established (Heller et al . 1974, Lyman & O’Brien 1974, Lyman et al .…”

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Is ‘nocturnal hypothermia’ a valid physiological concept in small birds?: a study on Bronze MannikinsSpermestes cucullatus

Lovegrove¹,

Smith²

2003

Ibis

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The thermoregulatory capacity and metabolic responses to light–dark cycles under various mild food‐deprivation treatments were measured in Bronze Mannikins Spermestes cucullatus (10–11 g). We measured the response of minimum oxygen consumption to ambient temperature in order to determine the basal metabolic rate (BMR), thermal conductance and limits of thermoneutrality of the Mannikins. In addition, we measured oxygen consumption in response to light–dark cycles and three mild food‐deprivation treatments. Bronze Mannikins have a low BMR (1.67 mlO2/g/h) that is c. 50–60% of that predicted from phylogenetically independent allometric curves for all birds. A low BMR resulted in amplitudes of metabolism between the active and rest phases that were double those predicted allometrically from body mass. The reduced nocturnal metabolic rate did not represent torpor. Typically, Mannikins would need to reduce their metabolic rate during the rest phase to c. 17% of BMR to attain the average torpor metabolic rate of other birds. The data are, however, consistent with those of other group‐living Afrotropical birds that benefit energetically from group huddling in environments in which moderate seasonality is accompanied by unpredictable climates – and thus unpredictable energy inputs in time and space. When food‐deprived and placed under moderate cold stress (20 °C), Mannikins decreased their rest‐phase metabolic rates to the same magnitude as several small Holarctic birds. We suggest that, in the context of the progress made to quantify and define proximate heterothermic responses in endotherms, such as torpor and hibernation, the term nocturnal hypothermia often applied to moderate nocturnal reductions in metabolic rate is vague, misleading and inappropriate.

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The Brain at Low Temperature: Tau Hyperphosphorylation Dynamics in Hibernation Torpor

Boerema¹,

Keijser

Bouma

et al. 2012

Living in a Seasonal World

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A comparison of temperature regulation in hibernating rodents

Cited by 23 publications

References 0 publications

Regulation of body temperature and energy requirements of hibernating Alpine marmots (Marmota marmota)

Regulation of body temperature and energy requirements of hibernating Alpine marmots (Marmota marmota)

Is ‘nocturnal hypothermia’ a valid physiological concept in small birds?: a study on Bronze MannikinsSpermestes cucullatus

The Brain at Low Temperature: Tau Hyperphosphorylation Dynamics in Hibernation Torpor

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