Threshold temperatures for shivering in acute and chronic hypercapnia

Schaefer, Karl E.; Wünnenberg, W.

doi:10.1152/jappl.1976.41.1.67

Cited by 37 publications

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“…However, the unique physiology of mammalian hibernators allows for active suppression of respiration during torpor, and under these conditions, blood pCO 2 increases to levels higher than those observed in metabolically active mammals [22,28,41,42]. This elevation of pCO 2 is thought to be an integral part of hibernation physiology as induction of an acidotic state serves to reduce metabolic rate and thermogenesis [25,43,44]. Additionally, the resultant high pCO 2 gradient improves ventilation efficiency, thereby minimizing energy costs of respiration during torpor [23].…”

Section: Discussionmentioning

confidence: 99%

White-nose syndrome initiates a cascade of physiologic disturbances in the hibernating bat host

et al. 2014

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Background: The physiological effects of white-nose syndrome (WNS) in hibernating bats and ultimate causes of mortality from infection with Pseudogymnoascus (formerly Geomyces) destructans are not fully understood. Increased frequency of arousal from torpor described among hibernating bats with late-stage WNS is thought to accelerate depletion of fat reserves, but the physiological mechanisms that lead to these alterations in hibernation behavior have not been elucidated. We used the doubly labeled water (DLW) method and clinical chemistry to evaluate energy use, body composition changes, and blood chemistry perturbations in hibernating little brown bats (Myotis lucifugus) experimentally infected with P. destructans to better understand the physiological processes that underlie mortality from WNS. Results: These data indicated that fat energy utilization, as demonstrated by changes in body composition, was two-fold higher for bats with WNS compared to negative controls. These differences were apparent in early stages of infection when torpor-arousal patterns were equivalent between infected and non-infected animals, suggesting that P. destructans has complex physiological impacts on its host prior to onset of clinical signs indicative of late-stage infections. Additionally, bats with mild to moderate skin lesions associated with early-stage WNS demonstrated a chronic respiratory acidosis characterized by significantly elevated dissolved carbon dioxide, acidemia, and elevated bicarbonate. Potassium concentrations were also significantly higher among infected bats, but sodium, chloride, and other hydration parameters were equivalent to controls.

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Section: Discussionmentioning

confidence: 99%

White-nose syndrome initiates a cascade of physiologic disturbances in the hibernating bat host

et al. 2014

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“…Several studies suggested that hypercapnia and hypoxia may induce or facilitate entry into torpor by suppressing metabolism (Studier and Baca, 1968;Williams and Rausch, 1973;Schäfer and Wünnenberg, 1976;Kuhnen et al, 1983). But there are also contrary observations described in the literature.…”

Section: Preparation For Entrance Into Torpormentioning

confidence: 95%

Cardiorespiratory and metabolic reactions during entrance into torpor in dormice, Glis glis

Elvert¹,

Heldmaier

2005

Journal of Experimental Biology

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Dormice voluntarily enter torpor at ambient temperatures ranging between 0-28°C. This study describes heart rate, ventilation frequency, O 2 -consumption (defined as metabolic rate), CO 2 -production and body temperature during entrance into torpor. Their temporal relationship was analysed during the time course of metabolic depression at different ambient temperatures. Body temperature and heart rate were measured in unrestrained dormice with implanted transmitter. Ventilation frequency was monitored by total body plethysmography or infrared video monitoring. To compare entries into torpor at different T a these periods were distinguished into four different phases: the resting phase prior to torpor, the phase of pre-torpor adjustments, the reduction phase and the phase of steady state torpor. In the pre-torpor phase, dormice increased their ventilation, metabolic rate and heart rate, indicating that the torpid state is initiated by an enhanced metabolic activity for about an hour. This was followed by a rapid reduction of ventilation, metabolism and heart rate, which reached their minimum values long before body temperature completed its decline. The results of the present study show that the entrance into torpor is caused by an active respiratory, cardiac and metabolic depression.

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“…Failure to detect any substantive reduction in mean Tb of muskrats resting in the hypercapnic atmosphere of the lodge also argues against the hypothesis of a lowered set point for Tb control. On the other hand, there is ample evidence in the literature that C 0 2 inhalation may suppress shivering and nonshivering thermogenesis in mammals exposed to cold (Pepelko and Dixon 1974;Schaefer and Wunnenberg 1976). In this study muskrats should not have encountered cold stress in Can.…”

Section: Discussionmentioning

confidence: 85%

Metabolic and behavioral responses of muskrats (Ondatra zibethicus) to elevated CO₂ in a simulated winter microhabitat

MacArthur¹

1986

Can. J. Zool.

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MACARTHUR, R. A. 1986. Metabolic and behavioral responses of muskrats (Ondatra zibethicus) to elevated C02 in a simulated winter microhabitat. Can. J. Zool. 64: 738-743. Metabolic and behavioral responses to inspired C02 were investigated in muskrats housed in a microhabitat designed to simulate winter field conditions. Mean daily rate of oxygen consumption (Vo2) declined from 1.46 mL 02.g. h-' in animals breathing room air to 1.11-1.25 mL 0 2 -g -h -' in animals inhaling 4-10% C02 in the simulated lodge. Daily patterns of Vo2, abdominal body temperature (Tb), and foraging activity were minimally affected by chronic C02 exposure, though muskrats breathing 9-10% C02 made shorter voluntary dives. The ability of muskrats to rewarm following foraging activity was slightly depressed by hypercapnia. Abrupt exposure of resting animals to ambient C02 levels of 10-16% often elicited avoidance reactions in the absence of any apparent change in Vo2 or Tb. This study provides the first demonstration of behavioral and metabolic responses by muskrats to C02 levels encountered in the winter microhabitat of this species. MACARTHUR, R. A. 1986. Metabolic and behavioral responses of muskrats (Ondatra zibethicus) to elevated C02 in a simulated winter microhabitat. Can. J. Zool. 64: 738-743.Les variations du mktabolisme et du comportement a l'inspiration de C02 ont fait I'objet d'une ktude chez des rats musquks gardks dans un microhabitat simulant les conditions naturelles en hiver. Le taux moyen quotidien de consommation d'oxygene (Vo2) a diminuk de 1,46 rnL O2.gm h-' a l'air ambiant a 1 , l l -1,25 mL 0 2 dans l'enceinte expkrimentale oh il y avait 4-10% de C02. L'exposition chronique au C02 n'a que tres peu affect6 les patterns journaliers de la consommation d'oxygene Vo2, de la tempkrature abdominale (Tb) ou de l'activitk de recherche de nourriture, bien que, chez les rats musquks soumis a la prksence de 9-10% de C02, les plongkes volontaires se soient averkes plus courtes. L'hypercapnie a eu aussi pour efffet de diminuer lkgerement la capacitk de rkchauffement des rats musquks apres une session de recherche de nourriture. L'exposition soudaine de rats musquks au repos a des concentrations klevkes de C02, de l'ordre de 10 a 16%, a souvent dkclenchk des rkactions de fuite en l'absence-de changements de V O~ ou de T b ~' e s t la premiere fois que les variations du mktabolisme et du comportement sont ktudikes chez des rats musquks mis en presence de concentrations de C02 de l'ordre de celles qui existent dans le microhabitat nature1 d'hiver de cette espece. ITraduit par la Revue]

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Threshold temperatures for shivering in acute and chronic hypercapnia

Cited by 37 publications

References 0 publications

White-nose syndrome initiates a cascade of physiologic disturbances in the hibernating bat host

White-nose syndrome initiates a cascade of physiologic disturbances in the hibernating bat host

Cardiorespiratory and metabolic reactions during entrance into torpor in dormice, Glis glis

Metabolic and behavioral responses of muskrats (Ondatra zibethicus) to elevated CO₂ in a simulated winter microhabitat

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Threshold temperatures for shivering in acute and chronic hypercapnia

Cited by 37 publications

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White-nose syndrome initiates a cascade of physiologic disturbances in the hibernating bat host

White-nose syndrome initiates a cascade of physiologic disturbances in the hibernating bat host

Cardiorespiratory and metabolic reactions during entrance into torpor in dormice, Glis glis

Metabolic and behavioral responses of muskrats (Ondatra zibethicus) to elevated CO2 in a simulated winter microhabitat

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Metabolic and behavioral responses of muskrats (Ondatra zibethicus) to elevated CO₂ in a simulated winter microhabitat