Cutaneous Water Loss at Rest and Exercise in Two Species of Marsupials

1983 ◽  
Vol 31 (1) ◽  
pp. 93 ◽  
Author(s):  
CJ Bell ◽  
RV Baudinette ◽  
SC Nicol
Keyword(s):  
Heat Loss ◽  
Brushtail Possum ◽  
Evaporative Heat Loss ◽  
Tasmanian Devil ◽  
Ambient Temperatures ◽  
Marsupial Species ◽  
Gland Function ◽  
A Minor ◽  
Cutaneous Evaporation ◽  
And Function

The relative roles of heat storage, evaporative, and non-evaporative heat loss were examined in the brushtail possum, Trichosurus vulpecula, and the Tasmanian devil, Sarcophilus harrisii, during exercise. Rates of water conductance across the skin were also measured at rest and while running at two ambient temperatures. Evaporative heat loss from the general body surface in S. harrisii is a minor contribution to the overall heat balance, and sweat gland function is not apparent. T. vulpecula relies more on heat loss mediated by cutaneous evaporation than from respiratory routes, but changes in cutaneous blood flow are more important than glandular activity in augmenting this response. These results and earlier reports in the literature suggest that the occurrence and function of cutaneous evaporation varies among marsupial species.

Inhibiting ventilatory evaporation produces an adaptive increase in cutaneous evaporation in mourning doves Zenaida macroura

1999 ◽  
Vol 202 (21) ◽  
pp. 3021-3028 ◽  
Author(s):  
T.C. Hoffman ◽  
G.E. Walsberg
Keyword(s):  
Skin Surface ◽  
The Body ◽  
Evaporative Heat Loss ◽  
Evaporative Water ◽  
Zenaida Macroura ◽  
Ambient Temperatures ◽  
Rapid Adjustment ◽  
Mourning Doves ◽  
A Minor ◽  
Cutaneous Evaporation

We tested the hypothesis that birds can rapidly change the conductance of water vapor at the skin surface in response to a changing need for evaporative heat loss. Mourning doves (Zenaida macroura) were placed in a two-compartment chamber separating the head from the rest of the body. The rate of cutaneous evaporation was measured in response to dry ventilatory inflow at three ambient temperatures and in response to vapor-saturated ventilatory inflow at two ambient temperatures. At 35 degrees C, cutaneous evaporation increased by 72 % when evaporative water loss from the mouth was prevented, but no increase was observed at 45 degrees C. For both dry and vapor-saturated treatments, cutaneous evaporation increased significantly with increased ambient temperature. Changes in skin temperature made only a minor contribution to any observed increase in cutaneous evaporation. This indicates that Z. macroura can effect rapid adjustment of evaporative conductance at the skin in response to acute change in thermoregulatory demand.

Changes in serotonin contents in brain affect metabolic heat production of rabbits in cold

1978 ◽  
Vol 235 (1) ◽  
pp. R41-R47
Author(s):  
M. T. Lin ◽  
I. H. Pang ◽  
S. I. Chern ◽  
W. Y. Chia
Keyword(s):  
Blood Flow ◽  
Amino Acid ◽  
Heat Loss ◽  
Acid Decarboxylase ◽  
Evaporative Heat Loss ◽  
Decarboxylase Inhibitor ◽  
Ambient Temperatures ◽  
Amino Acid Decarboxylase ◽  
Metabolic Heat ◽  
Normal Limits

Elevating serotonin (5-HT) contents in brain with 5-hydroxytryptophan (5-HTP) reduced rectal temperature (Tre) in rabbits after peripheral decarboxylase inhibition with the aromatic-L-amino-acid decarboxylase inhibitor R04-4602 at two ambient temperatures (Ta), 2 and 22 degrees C. The hypothermia was brought about by both an increase in respiratory evaporative heat loss (Eres) and a decrease in metabolic rate (MR) in the cold. At a Ta of 22 degrees C, the hypothermia was achieved solely due to an increase in heat loss. Depleting brain contents of 5-HT with intraventricular, 5,7-dihydroxytryptamine (5,7-DHT) produced an increased Eres and ear blood flow even at Ta of 2 degrees C. Also, MR increased at all but the Ta of 32 degrees C. However, depleting the central and peripheral contents of 5-HT with p-chlorophenylalanine (pCPA) produced lower MR accompanied by lower Eres in the cold compared to the untreated control. Both groups of pCPA-treated and 5,7-DHT-treated animals maintained their Tre within normal limits. The data suggest that changes in 5-HT content in brain affects the MR of rabbits in the cold. Elevating brain content of 5-HT tends to depress the MR response to cold, while depleting brain content of 5-HT tends to enhance the MR response to cold.

Respiratory water and heat loss of the black duck during flight at different ambient temperatures

1971 ◽  
Vol 49 (5) ◽  
pp. 767-774 ◽  
Author(s):  
M. Berger ◽  
J. S. Hart ◽  
O. Z. Roy
Keyword(s):  
Heat Loss ◽  
Water Loss ◽  
Pulmonary Ventilation ◽  
Evaporative Heat Loss ◽  
Total Heat Loss ◽  
Ambient Temperatures ◽  
Black Duck ◽  
Respiratory Heat Loss ◽  
Metabolic Water ◽  
Expired Air

Pulmonary ventilation and temperature of expired air and of the respiratory passages has been measured by telemetry during flight in the black duck (Anas rubripes) and the respiratory water and heat loss has been calculated.During flight, temperature of expired air was higher than at rest and decreased with decreasing ambient temperatures. Accordingly, respiratory water loss as well as evaporative heat loss decreased at low ambient temperatures, whereas heat loss by warming of the inspired air increased. The data indicated respiratory water loss exceeded metabolic water production except at very low ambient temperatures. In the range between −16 °C to +19 °C, the total respiratory heat loss was fairly constant and amounted to 19% of the heat production. Evidence for the independence of total heat loss and production from changes in ambient temperature during flight is discussed.

Effects of phentolamine on thermoregulatory functions of rats to different ambient temperatures

1979 ◽  
Vol 57 (12) ◽  
pp. 1401-1406 ◽  
Author(s):  
M. T. Lin ◽  
Andi Chandra ◽  
T. C. Fung
Keyword(s):  
Heat Loss ◽  
Rectal Temperature ◽  
Heat Production ◽  
Room Temperature ◽  
Metabolic Heat Production ◽  
Central Component ◽  
Evaporative Heat Loss ◽  
Central Administration ◽  
Ambient Temperatures ◽  
Metabolic Heat

The effects of both systemic and central administration of phentolamine on the thermoregulatory functions of conscious rats to various ambient temperatures were assessed. Injection of phentolamine intraperitoneally or into a lateral cerebral ventricle both produced a dose-dependent fall in rectal temperature at room temperature and below it. At a cold environmental temperature (8 °C) the hypothermia in response to phentolamine was due to a decrease in metabolic heat production, but at room temperature (22 °C) the hypothermia was due to cutaneous vasodilatation (as indicated by an increase in foot and tail skin temperatures) and decreased metabolic heat production. There were no changes in respiratory evaporative heat loss. However, in the hot environment (30 °C), phentolamine administration produced no changes in rectal temperature or other thermoregulatory responses. A central component of action is indicated by the fact that a much smaller intraventricular dose of phentolamine was required to exert the same effect as intraperitoneal injection. The data indicate that phentolamine decreases heat production and (or) increases heat loss which leads to hypothermia, probably via central nervous system actions.

Evaporative heat loss from group-housed growing pigs at high ambient temperatures

2007 ◽  
Vol 32 (5) ◽  
pp. 293-299 ◽  
Author(s):  
T.T.T. Huynh ◽  
A.J.A. Aarnink ◽  
M.J.W. Heetkamp ◽  
M.W.A. Verstegen ◽  
B. Kemp
Keyword(s):  
Heat Loss ◽  
Growing Pigs ◽  
Evaporative Heat Loss ◽  
Ambient Temperatures

Apparent latent heat of evaporation from clothing: attenuation and “heat pipe” effects

2008 ◽  
Vol 104 (1) ◽  
pp. 142-149 ◽  
Author(s):  
George Havenith ◽  
Mark G. Richards ◽  
Xiaoxin Wang ◽  
Peter Bröde ◽  
Victor Candas ◽  
...  
Keyword(s):  
Mass Loss ◽  
Heat Pipe ◽  
Heat Loss ◽  
Latent Heat ◽  
Heat Losses ◽  
Vapor Permeability ◽  
Thermal Manikin ◽  
Evaporative Heat Loss ◽  
Ambient Temperatures ◽  
Heat Of Evaporation

Investigating claims that a clothed person's mass loss does not always represent their evaporative heat loss (EVAP), a thermal manikin study was performed measuring heat balance components in more detail than human studies would permit. Using clothing with different levels of vapor permeability and measuring heat losses from skin controlled at 34°C in ambient temperatures of 10, 20, and 34°C with constant vapor pressure (1 kPa), additional heat losses from wet skin compared with dry skin were analyzed. EVAP based on mass loss ( Emass) measurement and direct measurement of the extra heat loss by the manikin due to wet skin ( Eapp) were compared. A clear discrepancy was observed. Emass overestimated Eapp in warm environments, and both under and overestimations were observed in cool environments, depending on the clothing vapor permeability. At 34°C, apparent latent heat (λapp) of pure evaporative cooling was lower than the physical value (λ; 2,430 J/g) and reduced with increasing vapor resistance up to 45%. At lower temperatures, λapp increases due to additional skin heat loss via evaporation of moisture that condenses inside the clothing, analogous to a heat pipe. For impermeable clothing, λapp even exceeds λ by four times that value at 10°C. These findings demonstrate that the traditional way of calculating evaporative heat loss of a clothed person can lead to substantial errors, especially for clothing with low permeability, which can be positive or negative, depending on the climate and clothing type. The model presented explains human subject data on EVAP that previously seemed contradictive.

scholarly journals Ancient Viral Integrations in Marsupials: A Potential Antiviral Defence

2021 ◽  
Author(s):  
Emma F Harding ◽  
Alice G Russo ◽  
Grace J H Yan ◽  
Paul D Waters ◽  
Peter A White
Keyword(s):  
Viral Infections ◽  
Active Role ◽  
Tammar Wallaby ◽  
Eutherian Mammal ◽  
Brushtail Possum ◽  
Replicase Gene ◽  
Tasmanian Devil ◽  
Available N ◽  
Marsupial Species ◽  
Australian Marsupial

Abstract Marsupial viruses are understudied compared to their eutherian mammal counterparts, although they may pose severe threats to vulnerable marsupial populations. Genomic viral integrations, termed endogenous viral elements (EVEs) could protect the host from infection. It is widely known past viral infections and EVEs play an active role in antiviral defence in invertebrates and plants. This study aimed to characterise actively transcribed EVEs in Australian marsupial species, because they may play an integral role in cellular defence against viruses. This study screened publicly available RNA sequencing datasets (n=35) and characterised 200 viral transcripts from thirteen Australian marsupial species. Of the 200 transcripts, 188 originated from either Bornaviridae, Filoviridae or Parvoviridae EVEs. The other 12 transcripts were from putative active infections from members of the Herpesviridae and Anelloviridae, and Hepadnaviridae. EVE transcripts (n=188) were mapped to marsupial genomes (where available, n=5/13) to identify the genomic insertion sites. Of the 188 transcripts, 117 mapped to 39 EVEs within the koala, bare-nosed wombat, tammar wallaby, brushtail possum and Tasmanian devil genomes. The remaining eight animals had no available genome (transcripts n=71). Every marsupial have Bornaviridae, Filoviridae and Parvoviridae EVEs, a trend widely observed in eutherian mammals. Whilst eutherian bornavirus EVEs are predominantly nucleoprotein-derived, marsupial bornavirus EVEs demonstrate a surprising replicase gene bias. We predicted these widely distributed EVEs were conserved within marsupials from ancient germline integrations, as many were over 65 million years old. One bornavirus replicase EVE, present in six marsupial genomes, was estimated to be 160 million years old, predating the American-Australian marsupial split. We considered transcription of these EVEs through small non-coding RNA as an ancient viral defence. Consistent with this, in koala small RNA sequence datasets we detected Bornaviridae replicase and Filoviridae nucleoprotein produced piRNA. These were enriched in testis tissue, suggesting they could protect marsupials from vertically transmitted viral integrations.

The role of the cholinergic systems in the central control of thermoregulation in rats

1979 ◽  
Vol 57 (11) ◽  
pp. 1205-1212 ◽  
Author(s):  
M. T. Lin ◽  
F. F. Chen ◽  
Y. F. Chern ◽  
T. C. Fung
Keyword(s):  
Heat Loss ◽  
Heat Production ◽  
Nerve Fibers ◽  
Cholinergic Receptors ◽  
Evaporative Heat Loss ◽  
Central Administration ◽  
Ambient Temperatures ◽  
Dose Dependent ◽  
Selective Blocker

Systemic and central administration of methacholine (a synthetic choline derivative) both produced dose-dependent decreases in rectal temperature in rats at all the ambient temperatures studied. Both at room temperature (22 °C) and in the cold (8 °C), the hypothermia in response to methacholine application was brought about by both a decrease in metabolic heat production and an increase in cutaneous circulation. In the heat (29 °C), the hypothermia was due solely to an increase in respiratory evaporative heat loss. Furthermore, the methacholine-induced hypothermia was antagonized by central pretreatment of atropine (a selective blocker of cholinergic receptors), but not by the central administration of either 6-hydroxy-dopamine (a relative depletor of catecholaminergic nerve fibers) or 5,6-dihydroxytryptamine (predominately a serotonin depletor). The data indicate that activation of the cholinergic receptors within brain with methacholine decreases heat production and (or) increases heat loss which leads to hypothermia in rats.

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