scholarly journals Behavioural responses of naked mole rats to acute hypoxia and anoxia

2017 ◽  
Vol 13 (12) ◽  
pp. 20170545 ◽  
Author(s):  
Aaron N. Ilacqua ◽  
Alexia M. Kirby ◽  
Matthew E. Pamenter
Keyword(s):  
Body Temperature ◽  
Metabolic Rate ◽  
Acute Hypoxia ◽  
Natural Habitat ◽  
Hypoxia Tolerance ◽  
Moderate Hypoxia ◽  
Behavioural Responses ◽  
Behavioural Activity ◽  
Acute Anoxia ◽  
Hypoxic Environment

Naked mole rats (NMRs) are among the most hypoxia-tolerant mammals. Other species respond to hypoxia by either escaping the hypoxic environment or drastically decreasing behavioural activity and body temperature ( T b ) to conserve energy. However, NMRs rarely leave their underground burrows, which are putatively hypoxic and thermally stable near the NMRs' preferred T b . Therefore, we asked whether NMRs are able to employ behavioural and thermoregulatory strategies in response to hypoxia despite their need to remain active and the minimal thermal scope in their burrows. We exposed NMRs to progressively deeper levels of hypoxia (from 21 to 0% O 2 ) while measuring their behaviour and T b . Behavioural activity decreased 40–60% in hypoxia and T b decreased slightly in moderate hypoxia (5–9%) and then further with deeper hypoxia (3% O 2 ). However, even at 3% O 2 NMRs remained somewhat active and warm, and continued to explore their environment. Remarkably, NMRs were active for greater than 90 s in acute anoxia and T b and metabolic rate decreased rapidly. We conclude that NMRs are adapted to remain awake and functional even at the extremes of their hypoxia-tolerance. This adaptation likely reflects variable and challenging levels of environmental hypoxia in the natural habitat of this species.

scholarly journals The decoupled nature of basal metabolic rate and body temperature in endotherm evolution

Nature ◽  
2019 ◽  
Vol 572 (7771) ◽  
pp. 651-654 ◽  
Author(s):  
Jorge Avaria-Llautureo ◽  
Cristián E. Hernández ◽  
Enrique Rodríguez-Serrano ◽  
Chris Venditti
Keyword(s):  
Body Temperature ◽  
Metabolic Rate ◽  
Basal Metabolic Rate

Relationship between metabolic rate and core body temperature during sleep in human

2015 ◽  
Vol 16 ◽  
pp. S186-S187 ◽  
Author(s):  
I. Park ◽  
M. Kayaba ◽  
K. Iwayama ◽  
H. Ogata ◽  
Y. Sengoku ◽  
...  
Keyword(s):  
Body Temperature ◽  
Metabolic Rate ◽  
Core Body Temperature ◽  
Core Body

On the Regulation of the Respiration in Reptiles

1961 ◽  
Vol 38 (2) ◽  
pp. 301-314 ◽  
Author(s):  
BODIL NIELSEN
Keyword(s):  
Steady State ◽  
Body Temperature ◽  
Metabolic Rate ◽  
Temperature Interval ◽  
Normal Values ◽  
Pulmonary Ventilation ◽  
The Body ◽  
Respiratory Frequency ◽  
Temperature Changes ◽  
Instantaneous Increase

1. In two species of Lacerta (L. viridis and L. sicula) the effects on respiration of body temperature (changes in metabolic rate) and of CO2 added to the inspired air were studied. 2. Pulmonary ventilation increases when body temperature increases. The increase is brought about by an increase in respiratory frequency. No relationship is found between respiratory depth and temperature. 3. The rise in ventilation is provoked by the needs of metabolism and is not established for temperature regulating purposes (in the temperature interval 10°-35°C). 4. The ventilation per litre O2 consumed has a high numerical value (about 75, compared to about 20 in man). It varies with the body temperature and demonstrates that the inspired air is better utilized at the higher temperatures. 5. Pulmonary ventilation increases with increasing CO2 percentages in the inspired air between o and 3%. At further increases in the CO2 percentage (3-13.5%) it decreases again. 6. At each CO2 percentage the pulmonary ventilation reaches a steady state after some time (10-60 min.) and is then unchanged over prolonged periods (1 hr.). 7. The respiratory frequency in the steady state decreases with increasing CO2 percentages. The respiratory depth in the steady state increases with increasing CO2 percentages. This effect of CO2 breathing is not influenced by a change in body temperature from 20° to 30°C. 8. Respiration is periodically inhibited by CO2 percentages above 4%. This inhibition, causing a Cheyne-Stokes-like respiration, ceases after a certain time, proportional to the CO2 percentage (1 hr. at 8-13% CO2), and respiration becomes regular (steady state). Shift to room air breathing causes an instantaneous increase in frequency to well above the normal value followed by a gradual decrease to normal values. 9. The nature of the CO2 effect on respiratory frequency and respiratory depth is discussed, considering both chemoreceptor and humoral mechanisms.

The liver proteome response to torpor in a basoendothermic mammal, Tenrec ecaudatus, provides insights into the evolution of homeothermy

2021 ◽  
Author(s):  
Jane I Khudyakov ◽  
Michael D Treat ◽  
Mikayla C Shanafelt ◽  
Jared S Deyarmin ◽  
Benjamin A Neely ◽  
...  
Keyword(s):  
Body Temperature ◽  
Metabolic Rate ◽  
Metabolic Pathways ◽  
Molecular Basis ◽  
Protein Abundance ◽  
Poor Control ◽  
High Body ◽  
Liver Proteome ◽  
The Common

Many mammals use adaptive heterothermy (e.g. torpor, hibernation) to reduce metabolic demands of maintaining high body temperature (Tb). Torpor is typically characterized by coordinated declines in Tb and metabolic rate (MR) followed by active rewarming. Most hibernators experience periods of euthermy between bouts of torpor during which homeostatic processes are restored. In contrast, the common tenrec, a basoendothermic Afrotherian mammal, hibernates without interbout arousals and displays extreme flexibility in Tb and MR. We investigated the molecular basis of this plasticity in tenrecs by profiling the liver proteome of animals that were active or torpid with high and more stable Tb (~32°C) or lower Tb (~14°C). We identified 768 tenrec liver proteins, of which 50.9% were differentially abundant between torpid and active animals. Protein abundance was significantly more variable in active cold and torpid compared to active warm animals, suggesting poor control of proteome abundance. Our data suggest that torpor in tenrecs may lead to mismatches in protein pools due to poor coordination of anabolic and catabolic processes. We propose that the evolution of endothermy leading to a more realized homeothermy of boreoeutherians likely led to greater coordination of homeostatic processes and reduced mismatches in thermal sensitivities of metabolic pathways.

Effect of 2,4-dinitrophenol on the hypometabolic response to hypoxia of conscious adult rats

1997 ◽  
Vol 83 (2) ◽  
pp. 537-542 ◽  
Author(s):  
Chikako Saiki ◽  
Jacopo P. Mortola
Keyword(s):  
Body Temperature ◽  
Oxidative Phosphorylation ◽  
Acute Hypoxia ◽  
Mammalian Species ◽  
Metabolic Effect ◽  
Adult Rats ◽  
Open Flow ◽  
Pharmacological Stimulation ◽  
Before And After ◽  
Mitochondrial Uncoupler

Saiki, Chikako, and Jacopo P. Mortola. Effect of 2,4-dinitrophenol on the hypometabolic response to hypoxia of conscious adult rats. J. Appl. Physiol. 83(2): 537–542, 1997.—During acute hypoxia, a hypometabolic response is commonly observed in many newborn and adult mammalian species. We hypothesized that, if hypoxic hypometabolism were entirely a regulated response with no limitation in O2availability, pharmacological uncoupling of the oxidative phosphorylation should raise O2consumption (V˙o 2) by similar amounts in hypoxia and normoxia. Metabolic, ventilatory, and cardiovascular measurements were collected from conscious rats in air and in hypoxia, both before and after intravenous injection of the mitochondrial uncoupler 2,4-dinitrophenol (DNP). In hypoxia (10% O2 breathing, 60% arterial O2 saturation),V˙o 2, as measured by an open-flow technique, was less than in normoxia (∼80%). Successive DNP injections (6 mg/kg, 4 times) progressively increasedV˙o 2 in both normoxia and hypoxia by similar amounts. Body temperature slightly increased in normoxia, whereas it did not change in hypoxia. The DNP-stimulatedV˙o 2 during hypoxia could even exceed the control normoxic value. A single DNP injection (17 mg/kg iv) had a similar metabolic effect; it also resulted in hypotension and a drop in systemic vascular resistance. We conclude that pharmacological stimulation ofV˙o 2 counteracts theV˙o 2 drop determined by hypoxia and stimulates V˙o 2not dissimilarly from normoxia. Hypoxic hypometabolism is likely to reflect a regulated process of depression of thermogenesis, with no limitation in cellular O2availability.

Dual core and shell temperature regulation during sea acclimatization in Gentoo penguins (Pygoscelis papua)

1994 ◽  
Vol 266 (4) ◽  
pp. R1319-R1326 ◽  
Author(s):  
E. Dumonteil ◽  
H. Barre ◽  
J. L. Rouanet ◽  
M. Diarra ◽  
J. Bouvier
Keyword(s):  
Body Temperature ◽  
Metabolic Rate ◽  
Thermal Insulation ◽  
Cold Water ◽  
Threshold Temperature ◽  
Ambient Temperatures ◽  
Adaptation To Cold ◽  
Marine Life ◽  
Shell Temperature ◽  
Skin Temperatures

Penguins are able to maintain a high and constant body temperature despite a thermally constraining environment. Evidence for progressive adaptation to cold and marine life was sought by comparing body and peripheral skin temperatures, metabolic rate, and thermal insulation in juvenile and adult Gentoo penguins exposed to various ambient temperatures in air (from -30 to +30 degrees C) and water (3-35 degrees C). Juvenile penguins in air showed metabolic and insulative capacities comparable with those displayed by adults. Both had a lower critical temperature (LCT) close to 0 degree C. In both adults and juveniles, the intercept of the metabolic curve with the abscissa at zero metabolic rate was far below body temperature. This was accompanied by a decrease in thermal insulation below LCT, allowing the preservation of a threshold temperature in the shell. However, this shell temperature maintenance was progressively abandoned in immersed penguins as adaptation to marine life developed, probably because of its prohibitive energy cost in water. Thus adaptation to cold air and to cold water does not rely on the same kind of reactions. Both of these strategies fail to follow the classical sequence linking metabolic and insulative reactions in the cold.

SOME PHYSIOLOGICAL AND NUTRITIONAL ASPECTS OF THE DWARF CHICKEN

1971 ◽  
Vol 51 (1) ◽  
pp. 209-216 ◽  
Author(s):  
G. RAJARATNAM ◽  
J. D. SUMMERS ◽  
A. S. WOOD ◽  
E. T. MORAN Jr.
Keyword(s):  
Body Weight ◽  
Oxygen Consumption ◽  
Weight Gain ◽  
Body Temperature ◽  
Metabolic Rate ◽  
Body Weight Gain ◽  
Carcass Composition ◽  
Lower Body ◽  
Brand Name ◽  
Dwarf Chicken

A study was undertaken to investigate the feasibility of hypothyroidism as an explanation for the smaller body size and lower metabolic activity of the recessive sex-linked dwarf chicken. A significant increase in body weight gain and feed intake for dwarf chicks with little change in these parameters for normal chicks receiving a diet supplemented with Protamone (brand name for iodinated casein) suggests a hypothyroidic state for the dwarfs. Similarly, a significantly lower body temperature, oxygen consumption and basal metabolic rate with a higher percentage of carcass fat in dwarf chicks as compared with normal ones supports the above hypothesis. Protamone supplementation of the diet increased body temperature and metabolic rate, and altered the carcass composition of the dwarfs to values closer to that of normal chicks, again suggesting a low thyroxine output for the dwarfs.

Embryos of eastern rainbowfish Melanotaenia splendida splendida (Peters, 1866) tolerate fluctuating hypoxia

2018 ◽  
Vol 69 (6) ◽  
pp. 987
Author(s):  
N. Flint ◽  
R. G. Pearson ◽  
M. R. Crossland
Keyword(s):  
Plant Material ◽  
Sublethal Effects ◽  
Larval Mortality ◽  
Natural Habitat ◽  
Hypoxia Tolerance ◽  
Hypoxic Exposure ◽  
Submerged Plant ◽  
Embryo Viability ◽  
Life History Stages ◽  
Egg Incubation

Hypoxia can have profound sublethal effects on reproduction and embryonic development of some freshwater fish. In the present study, the effects of diel fluctuating hypoxia on embryo viability were investigated for the eastern rainbowfish Melanotaenia splendida splendida, a small-bodied species common in wetlands of tropical Queensland. After daily hypoxic exposure (minimum 5% saturation) from fertilisation until hatch, no effects were found on egg incubation time, egg and larval mortality, and viability and size of hatching larvae. Older life history stages of the species are vulnerable to this level of hypoxia. Embryos of phytolithophilic species are likely exposed to fluctuating dissolved oxygen saturations in their natural habitat, and hypoxia tolerance may be a requirement for fish species that spawn predominantly on submerged plant material.

Effects of growth hormone transgenesis on metabolic rate, exercise performance and hypoxia tolerance in tilapia hybrids

2003 ◽  
Vol 63 (2) ◽  
pp. 398-409 ◽  
Author(s):  
D. J. McKenzie ◽  
R. Martínez ◽  
A. Morales ◽  
J. Acosta ◽  
R. Morales ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Metabolic Rate ◽  
Exercise Performance ◽  
Hypoxia Tolerance
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