Effect of aminophylline on metabolic and thermoregulatory responses during hypothermia associated with cold exposure in lambs

2003 ◽  
Vol 83 (4) ◽  
pp. 739-748 ◽  
Author(s):  
B. Zimmermann ◽  
G. Diebold ◽  
J. Galbraith ◽  
W. Whitmore ◽  
M. Okamoto ◽  
...  
Keyword(s):  
Body Weight ◽  
Metabolic Rate ◽  
Rectal Temperature ◽  
Heat Production ◽  
Cold Exposure ◽  
Phosphodiesterase Inhibitor ◽  
Rate Of Development ◽  
Dose Rates ◽  
Maximum Metabolic Rate ◽  
Response Trial

Three experiments were conducted with lambs to test the hypothesis that the phosphodiesterase inhibitor/adenosine blocker, aminophylline would enhance metabolic rate and delay the development of hypothermia. In exp. 1, eight lambs were treated either with aminophylline or control (0.9% saline) injections. During hypothermia, metabolic rate was increased from a resting value of 4.8 W kg-1 to maximum values of 15–16 W kg-1. The rate of development of hypothermia and recovery there from were inversely related to age and body weight. Aminophylline (8 mg kg-1) did not affect resting or maximum metabolic rate, but after a second injection, aminophylline increased metabolic rate after warming (P < 0.05) and tended to shorten the absolute period of time to restore normal rectal temperature (P < 0.10). In exp. 2, a dose-response trial with six lambs each receiving 0, 2, 16 or 32 mg aminophylline indicated that dose rates of 16 and 32 mg kg-1 increased (P < 0.05) metabolic rate of lambs. In exp. 3, 21 lambs received either 0.9% saline or aminophylline (24 mg kg-1) injections. Mean heat production ranged from 13 to 15 W kg-1 and was increased approximately 7% (P < 0.01) by aminophylline. Aminophylline, therefore, has some potential as a treatment for hypothermia or to improve recovery from hypothermia in lambs by increasing metabolic rate during cold stress. Key words: Lamb, metabolic rate, hypothermia, thermoregulation, Aminophylline®, phosphodiesterase inhibitor

Metabolic Factors in the Development of Homeothermy in Dogs

1958 ◽  
Vol 194 (2) ◽  
pp. 293-296 ◽  
Author(s):  
Donald G. McIntyre ◽  
H. E. Ederstrom
Keyword(s):  
Oxygen Consumption ◽  
Metabolic Rate ◽  
Rectal Temperature ◽  
Heat Production ◽  
Cold Exposure ◽  
Metabolic Factors ◽  
Air Temperatures ◽  
Heat Conservation

Dogs from 1 to 25 days of age were exposed to air temperatures of 5, 23 and 30°C and their oxygen consumption measured in a closed calorimeter. Animals 1–5 days old had a rise of 20–25% in metabolic rate, but rectal temperature fell, when they were exposed to 5 or 23°C. At 11–21 days of age dogs exposed to 5°C had a rise of about 75% in metabolic rate, but rectal temperature fell several degrees in 1 hour. In dogs 21–25 days of age metabolic rate increased about 75% at air temperatures of 5°C and rectal temperature fell only about 1°C. Under the same conditions a trained adult dog had a rise of 80% in metabolic rate, and no fall in rectal temperature. Since heat production in 2- to 3-week-old dogs was increased to about the same extent as in the adult on cold exposure, it was assumed that heat conservation lagged behind heat production in the development of homeothermy.

Effects of adrenaline and noradrenaline on the heat production of warm- and cold-acclimated sheep

1981 ◽  
Vol 59 (9) ◽  
pp. 985-993 ◽  
Author(s):  
A. D. Graham ◽  
R. J. Christopherson
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Dose Rate ◽  
Respiration Rate ◽  
Rectal Temperature ◽  
Heat Production ◽  
Cold Exposure ◽  
Gas Analysis ◽  
Dose Rates ◽  
Temperature Responses

The heat production (HP), heart rate (HR), respiration rate, rumen motility, and body temperature responses to 2.5-h adrenaline (A) and noradrenaline (NA) intrajugular infusions at 0.00, 0.15, 0.30, 0.60, and 0.90 μg∙kg−1∙min−1 were studied in 10 shorn wethers which had been chronically (3–8 weeks) exposed to warm (19–24 °C) or moderately cold (8–13 °C) temperatures. Heat production, as estimated from respired gas analysis, increased 40–45% with all doses of A and the effect was potentiated by chronic cold exposure. Only the higher dose rates of NA induced an increase in HP. The maximum HP increase due to NA was 30% and the effect was not influenced by chronic cold exposure. Thermoneutral HP was greater by 16–19% in cold-acclimated as compared with warm-acclimated sheep. Corresponding to the HP effects of A and NA, all doses of A and the highest dose of NA resulted in slight increases in rectal temperature. Respiration rate increased with increased dose rate of NA but only the highest dose of A resulted in an increase in respiration rate. HR, rectal temperature, and respiration rate responses to A and NA were not influenced by cold acclimation.

Effect of cold exposure on various sites of core temperature measurements

1983 ◽  
Vol 54 (4) ◽  
pp. 1025-1031 ◽  
Author(s):  
S. D. Livingstone ◽  
J. Grayson ◽  
J. Frim ◽  
C. L. Allen ◽  
R. E. Limmer
Keyword(s):  
Gastrointestinal Tract ◽  
Metabolic Rate ◽  
Heat Production ◽  
Cold Exposure ◽  
Local Heat ◽  
Control Environment ◽  
Body Temperatures ◽  
Cold Stimulation ◽  
Facial Cooling ◽  
Internal Body

Rectal, esophageal, auditory canal, gastrointestinal tract, and sublingual temperature were recorded on five young Caucasian males who, in an environment of -32 degrees C and 11-km/h wind, sat during one 90-min exposure and walked on a treadmill at 2.9 km/h during another. The clothing permitted cooling of their torsos while giving adequate protection to their extremities. Control exposures involved subjects sitting in still air at 24–26 degrees C dressed only in thermal underwear. In the control environment all of the internal body temperatures measured gave comparable and consistent values; however, cold exposure affected the various sites differently. Esophageal temperatures fluctuated rapidly as a result of subjects swallowing cold saliva. Sublingual temperatures were below the lower limit of a clinical thermometer, possibly because of facial cooling. Auditory canal temperatures were low, perhaps also because of facial cooling. Rectal temperatures were high as were the gastrointestinal tract temperatures, due perhaps to local heat production in response to cold stimulation. Metabolic rate increased initially in the cold and again toward the end of the cold exposure.

The effects of litter size, sex, age, body weight, dam age and genetic selection for cold resistance on the physiological responses to cold exposure of scottish blackface lambs in a progressively cooled water bath

1987 ◽  
Vol 45 (3) ◽  
pp. 477-491 ◽  
Author(s):  
A. W. Stott ◽  
J. Slee
Keyword(s):  
Body Weight ◽  
Metabolic Rate ◽  
Cold Exposure ◽  
Cold Resistance ◽  
Genetic Selection ◽  
Water Bath ◽  
Skin Thickness ◽  
Selection Line ◽  
Unit Body Weight ◽  
Total Body

ABSTRACTThe resistance to body cooling of 594 newborn Scottish Blackface lambs was measured in a water bath during a programme of upwards and downwards genetic selection. Cold resistance was defined as the time taken for rectal temperature to fall to 35°C in the water bath.Upwards selection produced increased cold resistance which was genetically associated with increased skin thickness, increased total body insulation and greater persistence of high metabolic rate during cold exposure. The first two correlated responses to selection were more pronounced in twins than in singles.High cold resistance was phenotypically, but not genetically, associated with greater body weight, increased coat depth and higher levels of cold-induced metabolic rate (heat production). Single lambs showed higher weight-adjusted metabolic rates and higher cold resistance than twins. Singles recovered from hypothermia faster than twins in the low selection line only.Female lambs showed higher metabolic rate (whether weight-adjusted or not) and greater total body insulation than males. Their greater cold resistance was not quite significant. Increasing age (range 0·3 to 36 h) was associated with a small but significant decline in cold resistance.Thermoneutral metabolic rate was proportional to body surface area, whereas peak metabolic rate was proportional to body weight such that peak metabolic rate per unit body weight was independent of changes in body weight. These findings are discussed in relation to lamb survival.

An improved water-bath test to study effects of age and previous sucking on metabolic rate and resistance to cold in newborn lambs

1990 ◽  
Vol 50 (2) ◽  
pp. 319-331 ◽  
Author(s):  
J. Slee ◽  
S. P. Simpson ◽  
A. W. Stott ◽  
J. C. Williams ◽  
D. E. Samson
Keyword(s):  
Body Weight ◽  
Metabolic Rate ◽  
Heat Production ◽  
Cold Resistance ◽  
Resting Metabolic Rate ◽  
Induced Hypothermia ◽  
Fast Cooling ◽  
Rate Of Cooling ◽  
Effect Of Age ◽  
Shivering Thermogenesis

ABSTRACTDifferent procedures for measuring cold resistance and metabolic rate of newborn lambs were evaluated by varying the extent of induced hypothermia, the rate of cooling and the method of rewarming. Relatively fast cooling followed by a simple self-rewarming procedure proved harmless and satisfactory.The effect of age, from birth up to 2 weeks, on thermoregulation was studied. There was no difference in cold resistance between 0·5 h and 30 h after birth, and between 1 day and 2 weeks after birth, despite a large increase in insulation, body weight and coat depth over this period. Weight-specific resting metabolic rate and cold-induced peak metabolic rate similarly did not change significantly in the first 30 h, although resting metabolic rate tended to be lower at birth than at 30 h of age. Peak metabolic rate decreased significantly between 1 day and 2 weeks of age.The effect of fasting, for 3 to 4 h after birth, on thermoregulation was also studied. Cold resistance and peak metabolic rate were not significantly affected by fasting. Recovery from hypothermia was slightly slower in fasted lambs.These results may reflect the newborn lamb's initial reliance on heat production derived from brown fat and non-shivering thermogenesis. Older lambs, which benefit from better insulation, rely more upon shivering. Fasted lambs showed a tendency to rely more on insulation and slightly less on heat production than suckled lambs.

scholarly journals SUMMIT METABOLISM OF NEWBORN CALVES WITH AND WITHOUT COLOSTRUM FEEDING

1986 ◽  
Vol 66 (4) ◽  
pp. 937-944 ◽  
Author(s):  
M. OKAMOTO ◽  
J. B. ROBINSON ◽  
R. J. CHRISTOPHERSON ◽  
B. A. YOUNG
Keyword(s):  
Body Weight ◽  
Metabolic Rate ◽  
Rectal Temperature ◽  
Cold Water ◽  
Water Immersion ◽  
Resting Metabolic Rate ◽  
The Body ◽  
Metabolic Rates ◽  
Colostrum Feeding ◽  
Time Required

Resting and summit metabolic rates were measured in 13 newborn (2.5–15 h old) male Holstein calves exposed to warm and cold tempertures in a water immersion system. Six calves were bottle fed 1 kg of colostrum 30 min before the measurements commenced. In the remaining seven calves, colostrum was withheld until after the end of the measurement period. There were no significant effects of colostrum feeding on resting or summit metabolic rates or the time required for rectal temperature to drop to 35 °C when the calves were immersed in cold water. The time required for rectal temperature to drop to 35 °C increased as the body weight of the calves increased; for each kilogram additional body weight, cooling was delayed for an extra 2.9 min. The resting metabolic rate averaged for both feeding treatments was 2.0 ± 0.1 W kg−1 while mean rectal temperature was 39.1 ± 0.2 °C. Mean summit metabolic rate was 7.2 ± 0.4 W kg−1 and occurred at a mean rectal temperature of 35.4 ± 0.3 °C. The average ratio of the summit to resting metabolic rate was 3.7 ± 0.2. Cooling via water immersion was associated with increases in plasma levels of glucose and free fatty acids. The feeding of 1 kg of colostrum 30 min prior to exposure to acute cold did not improve the apparent resistance of the calves to hypothermia. Key words: Newborn calf, summit metabolism, cold tolerance

Changing physiological relationships in men under acute cold stress

1970 ◽  
Vol 48 (1) ◽  
pp. 1-10 ◽  
Author(s):  
James F. O'Hanlon Jr. ◽  
Steven M. Horvath
Keyword(s):  
Rectal Temperature ◽  
Heat Production ◽  
Cold Exposure ◽  
Heat Content ◽  
Body Temperatures ◽  
Older Subjects ◽  
Skin Temperatures ◽  
Different Levels ◽  
Body Heat ◽  
Thigh Temperature

Thirty-four men were exposed to 8 °C for 2 h. Their reactions were studied to indicate how physiological relationships change during exposure to cold. Measurements of various body temperatures, MST, MBT, body heat content (BHC), [Formula: see text], heat production, and heart rate (HR) were made before the onset of and periodically during cold exposure. Various skin temperatures fell to different levels while rectal temperature rose slightly, then fell 0.3 °C by the end of the exposure. BHC declined by 6%, [Formula: see text] nearly doubled, [Formula: see text] and heat production increased by 66 and 75% respectively, and HR changed little during cold exposure. Relationships which changed most significantly during cold exposure were those between MST and rectal temperature, certain skin temperatures and rectal temperature, [Formula: see text] (also heat production) and BHC, [Formula: see text] and rectal temperature, and finally, those between every body temperature and the age of the subjects. Relationships which also changed were those between finger and toe temperature as well as those between [Formula: see text] (also heat production) and each of the following: [Formula: see text], rectal temperature, thigh temperature, HR, and age. These results indicated that (1) temperature in the upper extremities was actively maintained at a higher level than temperature in the lower extremities, (2) increased metabolism became a progressively more effective adaptation than redistribution of blood volume, (3) subjects with the lowest BHC tended to increase their metabolism the most, (4) [Formula: see text] was inversely related to core temperature after the latter fell below normal, (5) HR was unrelated to the increase in [Formula: see text], (6) the usual inverse relationship between age and metabolism was not found in the cold, and finally, (7) older subjects generally tended to maintain higher body temperatures than younger subjects.

Effects of oral glycine during cold exposure in man

1959 ◽  
Vol 14 (3) ◽  
pp. 390-392 ◽  
Author(s):  
William R. Beavers ◽  
Benjamin G. Covino
Keyword(s):  
Oxygen Consumption ◽  
Rectal Temperature ◽  
Heat Production ◽  
Cold Exposure ◽  
Human Subjects ◽  
Exposure Period ◽  
Blood Flows ◽  
Skin Temperatures ◽  
Warm Room

Six male human subjects were given 30 gm oral glycine. Oxygen consumption, skin and rectal temperatures, and forefinger blood flows were measured during an interval in a warm room and then during 75 minutes cold exposure (0°F). The same subjects receiving 30 gm glucose served as controls. Glycine increased heat production at rest in a warm room and also during cold exposure. The subjects when receiving glycine had a slightly higher rectal temperature and higher skin temperatures in areas other than fingers during the cold exposure period. Submitted on August 1, 1958

ÉTUDE DE L'ACCLIMATION THERMIQUE CHEZ LA LIMACE ARION CIRCUMSCRIPTUS

1963 ◽  
Vol 41 (4) ◽  
pp. 671-698 ◽  
Author(s):  
Adolphe Roy
Keyword(s):  
Body Weight ◽  
Oxygen Consumption ◽  
Metabolic Rate ◽  
Heat Production ◽  
Regression Line ◽  
Experimental Temperature ◽  
Acclimation Temperature ◽  
Direct Calorimetry

Slugs of the species Arion circumscriptus were acclimated to temperatures of 5°, 8° 10°, 20°, and 25 °C respectively. After acclimation, metabolic rate was determined, either as oxygen consumption, at 30° and 20°, or by direct calorimetry, at 25° and 12.5°, At all given exposure temperatures, the average metabolic rate was lower, by 1% to 1.5%, for each degree of increase in the acclimation temperature. When the logarithms of total O2 consumption or heat production per hour are plotted against the logarithms of body weight, the regression line obtained for slugs acclimated to heat stands below that obtained for slugs acclimated to cold; the slope is also slighter for the warm-acclimated slugs than for the cold-acclimated, so that the distance between corresponding points of two such curves is larger in the righthand side of the graph, where the large specimens are represented, than in the lefthand side where the small specimens are shown. This would imply that an increase in the acclimation temperature reduces metabolic rate to a proportionately greater extent in the larger specimens than it does in the smaller ones. The value of the slope, which is inversely correlated with acclimation temperature, is also inversely correlated with the experimental temperature at which metabolism is determined.

Seasonal acclimatization to cold in man

1961 ◽  
Vol 16 (2) ◽  
pp. 231-234 ◽  
Author(s):  
Thomas R. A. Davis ◽  
D. R. Johnston
Keyword(s):  
Surface Temperature ◽  
Rectal Temperature ◽  
Heat Production ◽  
Cold Exposure ◽  
Technical Assistance ◽  
Mean Value ◽  
Temperature Threshold ◽  
Total Period ◽  
A Value ◽  
Significant Change

Six subjects were measured once monthly from October to February for alterations in shivering, heat production, and rectal and skin temperatures produced by a standard cold exposure of 14.1 α 0.46°C for 1 hour. The responses of a second group of five subjects were measured once monthly from February to September during a cold exposure of 13.7 α 0.9°C. In the October-February group, shivering decreased to a January mean value 7% of the October figure ( P < 0.01). Cold-induced heat production decreased in February to a value 52% of the October figure ( P < 0.05). Mean rectal temperature and mean surface temperature over the total period of study showed no consistently significant change. The decrease in shivering was associated with a change in the surface temperature threshold of shivering onset. The February-September group showed an increase in shivering reaching a maximum in September ( P < 0.01). Again consistently significant alteration in surface or rectal temperature could not be demonstrated. The highly significant change in shivering and the less significant change in heat production observed suggests that man seasonally acclimatizes to cold and that this acquired acclimatization is lost during the summer months. Note: (With the Technical Assistance of F. C. Bell, W. Rawlings and L. Lee) Submitted on May 27, 1960

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