Temperature regulation in the new-born lamb. III. Effect of environmental temperature on metabolic rate body temperatures, and respiratory quotient

1961 ◽  
Vol 12 (6) ◽  
pp. 1152 ◽  
Author(s):  
G Alexander
Keyword(s):  
Body Temperature ◽  
Heat Loss ◽  
Heat Production ◽  
Temperature Regulation ◽  
Low Temperatures ◽  
Environmental Temperature ◽  
Body Temperatures ◽  
Normal Body Temperature ◽  
Ambient Temperatures ◽  
New Born

Studies were made on temperature regulation of lambs in a closed circuit indirect calorimeter. Dry new-born lambs were able to maintain normal body temperature in ambient temperatures as low as -5°C. This was accomplished by increasing heat production to 2–3 times "basal" levels, apparently by increased oxidation of fats, and by reducing heat loss through the extremities by vasoconstriction. The lower limit of the zone of thermal neutrality was about 29°C. In unsuckled lambs within 24 hr of birth, the heat produced in response to cold appeared to be independent of pre-natal nutrition and age. It was considerably lower in lambs with hairy coats than in lambs with fine coats. Milk intake increased heat production, and this increase was abolished after 12 hr of fasting in lambs up to 3 days old, but the increase persisted in older lambs. The increase was accompanied by, and was apparently due to, elevated heat loss from the extremities, which persisted even at low temperatures. The maximal thermal insulation of the tissues, calculated from these results, was about 1 Clo; that of the fleece plus air was only 1 to 2 Clo.

Temperature regulation in the new-born lamb. IV. The effect of wind and evaporation of water from the coat on metabolic rate and body temperature

1962 ◽  
Vol 13 (1) ◽  
pp. 82 ◽  
Author(s):  
G Alexander
Keyword(s):  
Metabolic Rate ◽  
Heat Loss ◽  
Heat Production ◽  
Temperature Regulation ◽  
Tap Water ◽  
High Heat ◽  
Cooling Efficiency ◽  
Experimental Conditions ◽  
Ambient Temperatures ◽  
New Born

The study of temperature regulation in new-born lambs has been extended from dry lambs in "still air" at various ambient temperatures to dry lambs in a wind of 550 cm sec-l, and to lambs whose coats are drying. Exposure to wind resulted in an increased slope of the line relating heat production to ambient temperature, but under the experimental conditions evaporation of water from the coat added approximately the same increment at all ambient temperatures. The effects of wind and evaporation at any one temperature appeared additive. The heat loss from naturally wet new-born lambs less than 1 hr old, in a wind, was greater than in slightly older lambs wetted with tap water. Lambs with hairy coats were able to conserve heat more readily than lambs with fine coats. The cooling efficiency of evaporation from the coat was about 25%. The elevation in temperature of the extremities which follows feeding and persists under conditions of moderate heat loss, appears to be almost abolished under conditions of high heat loss. During the studies on drying lambs, beat loss in many lambs exceeded heat production, and rectal temperature fell, which thus indicated the maximum possible heat production (summit metabolic rate) of which lambs are capable. Lambs from ewes on low or medium levels of feeding during pregnancy cooled more readily than lambs from well-fed ewes.

EXERCISE AND TEMPERATURE REGULATION IN LEMMINGS AND RABBITS

1955 ◽  
Vol 33 (1) ◽  
pp. 428-435 ◽  
Author(s):  
J. S. Hart ◽  
O. Heroux
Keyword(s):  
Oxygen Consumption ◽  
Body Temperature ◽  
Heat Production ◽  
Temperature Regulation ◽  
Thermal Equilibrium ◽  
Environmental Temperature ◽  
Body Temperatures ◽  
Temperature Changes ◽  
Extreme Cold ◽  
Environmental Temperatures

Oxygen consumption and body temperatures were determined in lemmings at environmental temperatures from 20 °C. to −10 °C. and in rabbits from 20 °C. to −50 °C. Body insulation indices were estimated as the ratio [Formula: see text]. In both species, increase in activity and decrease in temperature led to increases in oxygen consumption that were additive over the temperature range. Oxygen increments of work were independent of environmental temperature in the absence of progressive hypothermia. Work led to increases in body temperature at the upper environmental temperatures and to decreases in body temperature at the lower temperatures. In extreme cold, rabbits became progressively hypothermic during work and there was a decline in oxygen consumption. Body temperatures started to fall at environmental temperatures 18 °C. higher in working than in resting rabbits. Insulation was lower in working than in resting animals. During exercise there appears to be a readjustment of body temperature, insulation, and heat loss until thermal equilibrium is established. The regulation of heat production, within limits, seems to be independent of body-temperature changes during exercise.

EXERCISE AND TEMPERATURE REGULATION IN LEMMINGS AND RABBITS

1955 ◽  
Vol 33 (3) ◽  
pp. 428-435 ◽  
Author(s):  
J. S. Hart ◽  
O. Heroux
Keyword(s):  
Oxygen Consumption ◽  
Body Temperature ◽  
Heat Production ◽  
Temperature Regulation ◽  
Thermal Equilibrium ◽  
Environmental Temperature ◽  
Body Temperatures ◽  
Temperature Changes ◽  
Extreme Cold ◽  
Environmental Temperatures

Oxygen consumption and body temperatures were determined in lemmings at environmental temperatures from 20 °C. to −10 °C. and in rabbits from 20 °C. to −50 °C. Body insulation indices were estimated as the ratio [Formula: see text]. In both species, increase in activity and decrease in temperature led to increases in oxygen consumption that were additive over the temperature range. Oxygen increments of work were independent of environmental temperature in the absence of progressive hypothermia. Work led to increases in body temperature at the upper environmental temperatures and to decreases in body temperature at the lower temperatures. In extreme cold, rabbits became progressively hypothermic during work and there was a decline in oxygen consumption. Body temperatures started to fall at environmental temperatures 18 °C. higher in working than in resting rabbits. Insulation was lower in working than in resting animals. During exercise there appears to be a readjustment of body temperature, insulation, and heat loss until thermal equilibrium is established. The regulation of heat production, within limits, seems to be independent of body-temperature changes during exercise.

Learning in hypothermic rats

1963 ◽  
Vol 18 (5) ◽  
pp. 1016-1018 ◽  
Author(s):  
J. A. Panuska ◽  
Vojin Popovic
Keyword(s):  
Body Temperature ◽  
Temperature Regulation ◽  
Operant Behavior ◽  
Environmental Temperature ◽  
Experimental Situation ◽  
External Heat ◽  
Body Temperatures ◽  
White Rats ◽  
Survival Studies ◽  
Colonic Temperature

Inexperienced shaved adult white rats cooled to a colonic temperature of 18.5 C and then rewarmed to 26.0 C, were placed at an ambient temperature of 2.0 C with the possibility of using a lever-activated heat reinforcement apparatus. Their body temperatures leveled at 29 C; and during the next 40–80 min the rats either learned to press the lever systematically for external heat and thereby rewarmed themselves to euthermia, or they drifted into deeper hypothermia leading to death. Activity records and visual observations indicate that after an average of 48 min and at a body temperature of 29.6 C (28.5–30.2 C), out of a group of 14 rats 12 learned this technique necessary for their survival. All 12 rats reached euthermia and continued to use the lever as long as they remained in the experimental situation. It is concluded that learning is possible even at a low body temperature of 29.6 C. performance; heat reinforcement; temperature regulation; body temperature; environmental temperature; operant behavior; survival studies; motivation; physiology of learning; cold physiology Submitted on March 7, 1963

scholarly journals Development of temperature regulation in newborn reindeer

Rangifer ◽  
1981 ◽  
Vol 1 (1) ◽  
pp. 29 ◽  
Author(s):  
R. Hissa ◽  
S. Saarela ◽  
M. Nieminen
Keyword(s):  
Nervous System ◽  
Body Temperature ◽  
Sympathetic Nervous System ◽  
Metabolic Rate ◽  
Heat Production ◽  
Temperature Regulation ◽  
Rangifer Tarandus ◽  
Normal Body Temperature ◽  
Newborn Calves ◽  
Sympathetic Nervous

<p>Development of temperature regulation was investigated by determining the ability of newborn reindeer calves (Rangifer tarandus tarandus) to maintain a normal body temperature when exposed to an incrementially decreasing ambient temperature. Newborn calves (1 day old) can maintain their body temperature even at -15 &deg;C. They can increase their metabolic rate five- to sixfold. Heat production is primarily stimulated by the sympathetic nervous system. The response to exogenous administration of noradrenaline and propranolol was investigated.</p><p>Poronvasan l&aring;mmons&aring;&aring;telyn syntym&aring;nj&aring;lkeinen kehittyminen.</p><p>Abstract in Finnish / Yhteenveto: Vastasyntyneiden poronvasojen kylmansietoa ja lammonsaatelya tutkittiin toukokuussa 1981 Inarin Kaamasessa Paliskuntain yhdistyksen koetarhassa. Tutkittavat vasat olivat 1-10 vuorokauden ikaisia. Vasa asetettiin j&aring;&aring;hdytett&aring;va&aring;n mittauskammioon. Sen aineenvaihdunta, lampotilat niin ihon eri kohdista kuin perasuolesta, lihasvarina ja sydanfrekvenssi rekisteroitiin jatkuvasti. Tulosten mukaan naytt&aring;a silt&aring; kuin 1 vuorokauden ikaiselle vasalle -15 &deg;C olisi ehdoton alaraja l&aring;mpotilan s&aring;&aring;telyssa. Se kykeni kohottamaan hapenkulutusta talloin 5-kertaisesti. Lihasvarinan merkitys on vahainen verrattuna kemialliseen l&aring;mmontuottoon kylmassa. Tama voitiin osoittaa injisoimalla vasaan sympaattisen hermoston valittajaainetta noradrenaliinia.</p><p>Temperaturreguleringens utvikling hos nyf&oslash;dte reinkalver.</p><p>Abstract in Norwegian / Sammendrag: Temperaturreguleringens utvikling er studert ved &aring; bestemme nyf&oslash;dte reinkalvers evne til &aring; opprettholde normal kroppstemperatur under p&aring;virkning av gradvis synkende omgivelsestemperatur. Nyf&oslash;dte kalver (1 d&oslash;gn gamle) kan opprettholde sin kroppstemperatur selv ved -15 &deg;C. De kan &oslash;ke sin omsetningshastighet fem til seks ganger. I starten er varmeproduksjonen stimulert av det sympatiske nervesystem. Virkningen av tilf&oslash;rt noradrenalin og propranolol ble studert og skjelving synes &aring; spille bare en mindre rolle umiddelbart etter f&oslash;dselen.</p>

Thermoregulatory and metabolic changes during fever in young and old rats

2003 ◽  
Vol 285 (5) ◽  
pp. R1165-R1169 ◽  
Author(s):  
Jessica B. Buchanan ◽  
Elizabeth Peloso ◽  
Evelyn Satinoff
Keyword(s):  
Metabolic Rate ◽  
Heat Loss ◽  
Heat Production ◽  
Metabolic Changes ◽  
Body Temperatures ◽  
Ambient Temperatures ◽  
Young Rats ◽  
Heat Conservation ◽  
Old Rats ◽  
S Peak

We injected old and young rats with lipopolysaccharide (LPS; 50 μg/kg ip) at two ambient temperatures ( Ta; 21 and 31°C). Young rats mounted equivalent fevers at both Tas [peak body temperatures ( Tb) of 38.3 and 38.7°C, respectively]. The Tbof old rats was not different from baseline (37.3°C) after LPS at Ta21°C, whereas, at 31°C, their Tbrose to a mean peak of 38.4°C. We also measured the associated thermoregulatory responses by use of calorimetry. At 21°C, young rats developed a fever by increasing both O2consumption and heat conservation. Old rats did not become febrile, and O2consumption fell by 15%. Heat loss was the same in old and young rats. At 31°C, young and old rats developed similar fevers with similar increases in heat production and conservation. Our results suggest that the lack of LPS fever in old rats at 21°C is due mainly to the lowered metabolic rate.

CALORIMETRIC DETERMINATION OF AVERAGE BODY TEMPERATURE OF SMALL MAMMALS AND ITS VARIATION WITH ENVIRONMENTAL CONDITIONS

1951 ◽  
Vol 29 (3) ◽  
pp. 224-233 ◽  
Author(s):  
J. S. Hart
Keyword(s):  
Body Temperature ◽  
Heat Production ◽  
Temperature Rise ◽  
Environmental Temperature ◽  
Body Temperatures ◽  
Dewar Flask ◽  
Air Temperatures ◽  
Calorimetric Determination ◽  
Average Body

A method is described for determining average body temperature of mice by placing them immediately after killing in a Dewar flask containing water and recording the temperature rise. Evidence is presented to show that postmortem heat production does not contribute appreciably to the results. Average body temperatures are usually about 2 °C. lower than colonic temperatures except during lethal chilling when average temperatures are frequently higher than colonic. The rise in average body temperature produced by activity increases with environmental temperature. Body temperatures may be lower during activity than during rest at cold air temperatures.

Thermoregulatory effects of methoxamine and isoprenaline following injections into the cerebral ventricles of conscious rabbits

1977 ◽  
Vol 55 (4) ◽  
pp. 821-827 ◽  
Author(s):  
D. L. Jones ◽  
W. L. Veale ◽  
K. E. Cooper
Keyword(s):  
Body Temperature ◽  
Ambient Temperature ◽  
Heat Loss ◽  
Heat Production ◽  
Adrenergic Receptors ◽  
Cerebral Ventricles ◽  
Inhibitory Neurotransmitter ◽  
Ambient Temperatures ◽  
Hypothalamic Preoptic Area ◽  
Dose Dependent

There is evidence to suggest that within the hypothalamus noradrenaline (NA) is an inhibitory neurotransmitter acting on both the heat production and heat loss pathways in the rabbit. Further, it has been proposed that the inhibition of the heat loss pathway which results in hyperthermia is mediated primarily through α-adrenergic receptors within the anterior hypothalamic–preoptic area. We have investigated the effects of the α-receptor agonist methoxamine, administered directly into the cerebral ventricles, on body temperature at various ambient temperatures in both the shorn and unshorn rabbit. At all ambient temperatures tested, administration of methoxamine into a lateral cerebral ventricle produced a gradual dose-dependent hyperthermia. The magnitude of the hyperthermic response diminished with decreasing ambient temperatures. It is already known that the β-adrenergic agonist isoprenaline produces little or no effect on body temperature following intracranial application at ambient temperatures above 18 °C. In our experiments conducted at the lower ambient temperature, it produced a pronounced dose-dependent fall in body temperature in the shorn rabbit. The results of this work support the suggestion that NA can act as an inhibitory substance on the heat production or heat loss pathway in the rabbit. Which pathway is inhibited at any one time is dependent on the ambient temperature. Further, it would appear that inhibition of the heat loss pathway is largely mediated through α-adrenergic receptors, whilst the inhibition of the heat production pathway is mediated to a large extent through β-adrenergic receptors.

Thermal effects on locomotion in the nocturnal gecko Homonota darwini (Gekkonidae)

2007 ◽  
Vol 28 (2) ◽  
pp. 235-246 ◽  
Author(s):  
Marianne Renner ◽  
Víctor Cussac ◽  
Nora Ibargüengoytía ◽  
Carla Piantoni ◽  
Jorgelina Boretto
Keyword(s):  
Body Temperature ◽  
Low Temperatures ◽  
Thermal Effects ◽  
Environmental Temperature ◽  
Resource Acquisition ◽  
Body Temperatures ◽  
Night Time ◽  
Running Speed ◽  
Rio Negro ◽  
The World

AbstractNocturnal lizards show a complex adaptation to environmental temperature. They obtain heat from the substratum, using daytime for performing physiological functions inside thermally suitable shelters, and night-time which involves locomotion and loss of heat for capturing prey. Homonota darwini, the southernmost geckonid in the world, is a small nocturnal insectivorous gecko that occurs in saxicolous habitats of Patagonia, Argentina. Geckos were captured by hand during the day on a rocky hill near Bariloche (Río Negro, Argentina) in spring and summer. All the geckos were active during daytime and had good limb mobility with a median body temperature of 23°C. Body temperatures showed a direct dependence on the temperature of the roof of the shelter and on the air temperature. Geckos were made to run on a horizontal track and running speed was measured in two experiments: long runs (1 m) and sprint runs (0.20 m) during the day (diurnal) and at night (nocturnal). Speed was significantly greater in sprints than in long runs and speed increased with body temperature, reaching a maximum at a body temperature of 22°C. Thus, we conclude that, although the low temperatures of Patagonia impose heavy constraints on the physiological performance of Homonota darwini, they have a peculiar arrangement of mechanical and biochemical abilities which allows for resource acquisition at night, using cryptic habits and short sprint runs.

scholarly journals Human thermoregulatory responses during serial cold-water immersions

1998 ◽  
Vol 85 (1) ◽  
pp. 204-209 ◽  
Author(s):  
John W. Castellani ◽  
Andrew J. Young ◽  
Michael N. Sawka ◽  
Kent B. Pandolf
Keyword(s):  
Body Temperature ◽  
Rectal Temperature ◽  
Heat Production ◽  
Alternative Explanation ◽  
Cold Water ◽  
Metabolic Heat Production ◽  
Normal Body Temperature ◽  
Repeat Trial ◽  
Metabolic Heat ◽  
Made In

This study examined whether serial cold-water immersions over a 10-h period would lead to fatigue of shivering and vasoconstriction. Eight men were immersed (2 h) in 20°C water three times (0700, 1100, and 1500) in 1 day (Repeat). This trial was compared with single immersions (Control) conducted at the same times of day. Before Repeat exposures at 1100 and 1500, rewarming was employed to standardize initial rectal temperature. The following observations were made in the Repeat relative to the Control trial: 1) rectal temperature was lower and heat debt was higher ( P < 0.05) at 1100; 2) metabolic heat production was lower ( P < 0.05) at 1100 and 1500; 3) subjects perceived the Repeat trial as warmer at 1100. These data suggest that repeated cold exposures may impair the ability to maintain normal body temperature because of a blunting of metabolic heat production, perhaps reflecting a fatigue mechanism. An alternative explanation is that shivering habituation develops rapidly during serially repeated cold exposures.

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