Thermoregulation in Exercising White Rats

1973 ◽  
Vol 51 (11) ◽  
pp. 814-824 ◽  
Author(s):  
K. Myhre ◽  
B. Hellstrøm
Keyword(s):  
Thermal Stress ◽  
Skin Temperature ◽  
Albino Rats ◽  
Cold Environment ◽  
Exercise Time ◽  
Ambient Temperatures ◽  
Warm Environment ◽  
White Rats ◽  
Skin Temperatures ◽  
Trunk Skin

Colonic temperatures (TC), heart rates (HR), back skin and tail skin temperatures (TST) were measured in six warm acclimated (+24 °C) male albino rats running on a treadmill at three different work loads (HR ranging from 400 beats/min to 500 beats/min). Ambient temperatures (TA) ranged from about +8 °C to about +30 °C. TC increased immediately upon onset of work. Exercising in a cold environment ultimately made the rats hypothermic and in a warm environment hyperthermic. Within the limits set by the external thermal stress the rats controlled TC independently of the work intensity.High trunk skin temperatures were recorded in all experiments. Exercise in cold and cool environments produced tail skin vasoconstriction. In the 21 °C environment half of the rats produced tail skin vasodilation. In the 28 °C environment most experiments produced this effect. Cessation of work was accompanied by prompt vasoconstriction. The results indicated that exercise time before tail vasodilation was affected by exercise as well as by the tail skin temperature prior to vasodilation.

Extremity skin temperature in British and Zebu cross cattle

1967 ◽  
Vol 69 (1) ◽  
pp. 1-7 ◽  
Author(s):  
K. G. Johnson ◽  
M. E. D. Webster
Keyword(s):  
Skin Temperature ◽  
Lower Leg ◽  
Zebu Cattle ◽  
Temperature Changes ◽  
Ambient Temperatures ◽  
Thermal Environments ◽  
Air Temperatures ◽  
Environmental Temperatures ◽  
Skin Temperatures ◽  
Trunk Skin

1. Extremity skin temperature changes in British and Zebu cross cattle examined in moderate thermal environments followed a thermoregulatory pattern similar to that describedby Whittow (1962). At low environmental temperatures, ear and lower leg skin temperatures were usually only slightly above air temperature. At a variable time after air temperatures began to rise or the animals were fed, extremity skin temperatures increased suddenly to near trunk skin temperature.2. In eight of the ten pairs of animals studied in rising ambient temperatures and during feeding after fasting for 36–72 hr, increases in ear temperature were measured in the British animal before similar changes occurred in its Zebu counterpart. Changes in lower leg skin temperature followed a similar pattern.Trunk skin temperatures and respiratory frequencies were significant higher in British cross animals than in Zebu cross animals of similar thermal history. The mean rectal temperature of both British and Zebu cattle was 38·5 °C.

Forearm blood flow during body temperature transients produced by leg exercise

1975 ◽  
Vol 38 (1) ◽  
pp. 58-63 ◽  
Author(s):  
C. B. Wenger ◽  
M. F. Roberts ◽  
J. A. Stolwijk ◽  
E. R. Nadel
Keyword(s):  
Blood Flow ◽  
Skin Temperature ◽  
Forearm Blood Flow ◽  
Bicycle Ergometer ◽  
Vapor Pressures ◽  
Internal Temperature ◽  
Ambient Temperatures ◽  
Forearm Skin ◽  
Leg Exercise ◽  
Skin Temperatures

Subjects exercised for 30 min on a bicycle ergometer at 30, 50, and 70% of maximal aerobic power in ambient temperatures of 15, 25, and 35 degrees C and vapor pressures of less than 18 Torr. Exercise was used to vary internal temperature during an experiment, and different ambient temperatures were used to vary skin temperatures independently of internal temperature. Forearm skin temperature was fixed at about 36.5 degrees C. Esophageal temperature (Tes) was measured with a thermocouple at the level of the left atrium, and mean skin temperature (Tsk) was calculated from a weighted mean of thermocouple temperatures at eight skin sites. Forearm blood flow (BF) was measured by electrocapacitance plethysmography. Our data are well accounted for by an equation of the form BF = a1Tes + q2Tsk + b, independent of exercise intensity, although some subjects showed an equivocal vasodilator effect of exercise. The ratios a1/a2 (7.5, 9.6, 11.7) are quite similar to the ratios (8.6, 10.4) of the corresponding coefficients in two recent models of thermoregulatory sweating.

Shorn and unshorn Awassi sheep IV. Skin temperature and changes in temperature and humidity in the fleece and its surface

1963 ◽  
Vol 60 (2) ◽  
pp. 183-193 ◽  
Author(s):  
E. Eyal
Keyword(s):  
Ambient Temperature ◽  
Skin Temperature ◽  
Vapour Pressure ◽  
The Sun ◽  
Direct Sunlight ◽  
Ambient Temperatures ◽  
Awassi Sheep ◽  
Break Points ◽  
Environmental Temperatures ◽  
Skin Temperatures

1. A comparison was made between the skin temperature, humidity and temperature within and on the surface of the fleece of unshorn and shorn sheep. This study was conducted during various seasons of the year, at different environmental temperatures, while sheep were maintained in the shade or subjected to direct sunlight.2. Accompanying the rise of ambient temperature (in the shade) from 10 to 43° C. there was an increase in skin temperature from 34 to 40° C. and from 28 to 40° C. of the unshorn and shorn sheep, respectively.3. The relationship between the rise in skin temperature and that of ambient temperature was not linear, but showed a stepwise pattern in which the ‘breaks’ occurred at similar environmental temperatures for both groups, although skin temperatures of shorn sheep were lower than the unshorn.4. The diurnal change in skin temperature of the shorn sheep was similar to that of the ambient temperature. The decrease in skin temperature of unshorn sheep sometimes lagged behind the fall in environmental temperature. The seasonal variations between summer and winter were more significant in shorn than in unshorn sheep.5. Fleece surface temperatures measured at the same ambient temperatures ranged between 13 and42° C. and 16·5–39·5° C. in the unshorn and shorn sheep, respectively. In the break points of the rise in skin temperature, there occurred a drop in temperature gradients between the skin and fleece surface. This probably indicates a rise in thermal conductivity of the fleece at these points.6. The temperature gradient per unit of fleece thickness is inversely related to the depth of fleece and is greater the nearer to the skin.7. With exposure to the sun, skin temperatures of both groups greatly increased and occasionally reached 47° C. Under these conditions the differences between shorn and unshorn groups were not consistent.8. Fleece temperatures of unshorn sheep increased greatly upon exposure to the sun. The maximal temperatures were recorded midway between the fleece surface and skin. These temperatures generally reached 55° C. and sometimes even exceeded 60° C.9. At ambient temperatures of 30–35° C. the vapour pressure close to the skin of unshorn sheep ranged between 35–40 mm. Hg. With shorn sheep, however, the vapour pressure close to the skin was similar to that of the environment. In Yotvata there was a rise in vapour pressure close to the skin when the ambient temperature increased to 40–43° C. This rise in humidity was paralleled by a rise of vapour pressure throughout the wool. It was not linear but rather showed a ‘step-wise’ pattern.10. The vapour pressure in fleece and near the skin of sheep subjected to direct sunlight increased considerably (up to 80 mm. Hg). This rise showed a wave-like curve with various degrees of persistency. Appearance of fluid on the skin of Awassi sheep was observed on several occasions.

Effects of apomorphine on thermoregulatory responses of rats to different ambient temperatures

1979 ◽  
Vol 57 (5) ◽  
pp. 469-475 ◽  
Author(s):  
M. T. Lin ◽  
Y. F. Chern ◽  
Zyx Wang ◽  
H. S. Wang
Keyword(s):  
Skin Temperature ◽  
Dopamine Neurons ◽  
Induced Hypothermia ◽  
Evaporative Heat Loss ◽  
Central Administration ◽  
Mean Skin Temperature ◽  
Ambient Temperatures ◽  
6 Hydroxydopamine ◽  
Sites Of Action ◽  
Skin Temperatures

Either systemic or central administration of apomorphine produced dose-related decreases in rectal temperature at ambient temperatures (Ta) of 8 and 22 °C in rats. At Ta = 8 °C, the hypothermia was brought about by a decrease in metabolic rate (M). At Ta = 22 °C, the hypothermia was due to an increase in mean skin temperature, an increase in respiratory evaporative heat loss (Eres) and a decrease in M. This increased mean skin temperature was due to increased tail and foot skin temperatures. However, at Ta = 29 °C, apomorphine produced increased rectal temperatures due to increased M and decreased Eres. Moreover, the apomorphine-induced hypothermia or hyperthermia was antagonized by either haloperidol or 6-hydroxydopamine, but not by 5,6-dihydroxytryptamine. The data indicate that apomorphine acts on dopamine neurons within brain, with both pre- and post-synaptic sites of action, to influence body temperature.

Oxygen consumption and body temperature during sleep in cold environments

1959 ◽  
Vol 14 (5) ◽  
pp. 765-767 ◽  
Author(s):  
M. B. Kreider ◽  
P. F. Iampietro
Keyword(s):  
Oxygen Consumption ◽  
Body Temperature ◽  
Skin Temperature ◽  
Ambient Temperatures ◽  
Cold Environments ◽  
Body Cooling ◽  
Skin Temperatures ◽  
Body Heat

Six young soldiers slept at the following ambient temperatures: 25.5° to 26℃ (78–80℉), 15° to 18.5°C (60°–65℉) and -32° to -34.5℃ (-25°--30℉). Rectal (Tr) and skin temperatures were recorded and mean weighted skin temperature (Ts) was calculated at -hour intervals every night; oxygen consumption (Vo2) was measured at 6-minute intervals on occasional nights. During sleep at a ‘comfortable’ temperature (25.5℃) Tr, Ts and Vo2 decreased below the resting levels measured just before retiring. During sleep in cold environments, Tr and Ts dropped to still lower levels with the lowest values recorded at an early hour of the night. Vo2 during sleep in the cold did not differ from values recorded during sleep at 25.5℃. Lowest values measured during sleep in the coldest environment were 35.5°C, 30.5℃ and 78 Cal/m2 for Tr, Ts and body heat debt, respectively. These values may represent the limits of body cooling compatible with substantially continuous sleep in the cold. Submitted on February 19, 1959

Effect of ketamine on thermoregulation in rats

1978 ◽  
Vol 56 (6) ◽  
pp. 963-967 ◽  
Author(s):  
M. T. Lin ◽  
C. F. Chen ◽  
I. H. Pang
Keyword(s):  
Drug Treatment ◽  
Skin Temperature ◽  
Rectal Temperature ◽  
Heat Production ◽  
Intraperitoneal Administration ◽  
Metabolic Heat Production ◽  
Ambient Temperatures ◽  
Metabolic Heat ◽  
Dose Dependent ◽  
Skin Temperatures

Intraperitoneal administration of ketamine produced dose-dependent hypothermia at the ambient temperatures (Ta) of both 8 and 23 °C in unanesthetized rats. At a Ta of 8 °C, the hypothermia was brought about solely by a decrease in metabolic heat production. There were no changes in either the tail skin temperature (Ttail) or the sole skin temperature (Tsole). At a Ta of 23 °C, the hypothermia was due to an increase in Ttail, an increase in Tsole, and a decrease in metabolic heat production. However, at a Ta of 31 °C, there were no changes in rectal temperature in response to ketamine application, since neither heat production nor skin temperatures (e.g., Ttail and Tsole) was affected by ketamine at this Ta. The data indicate that the effect of the drug treatment may be to decrease heat production and (or) increase heat loss.

Human Performance in the Cold

1967 ◽  
Vol 9 (3) ◽  
pp. 203-220 ◽  
Author(s):  
William F. Fox
Keyword(s):  
Reaction Time ◽  
Skin Temperature ◽  
Human Performance ◽  
Cold Environment ◽  
Tactile Sensitivity ◽  
Ambient Temperatures ◽  
Manual Performance ◽  
Competing Stimuli

The literature dealing with human performance in the cold is reviewed. Seven major areas are discussed: a) tactile sensitivity, b) manual performance, c) tracking, d) reaction time, e) complex behaviors, f) maintaining hand skin temperature (HST) as a means of maintaining operator effectiveness, and g) adaptation and acclimatization to low ambient temperatures. Performance decrements at low ambient temperatures appear to result principally from lowered HST and competing stimuli provided by the cold environment.

Cold Vasodilatation of the Rat Tail

1975 ◽  
Vol 53 (2) ◽  
pp. 207-210 ◽  
Author(s):  
B. Hellström
Keyword(s):  
Skin Temperature ◽  
Temperature Increase ◽  
Onset Time ◽  
Albino Rats ◽  
Peak Time ◽  
Ambient Temperatures ◽  
Air Temperatures ◽  
Ice Water ◽  
Rat Tail

The tail-skin temperature was measured in nine male albino rats resting at chamber air temperatures between 40 and 16 °C. Spontaneous increases of tail temperature, strongly indicative of cold-induced vasodilatations (CIVD), were evoked by immersing the tail in ice water. The reproducibility of onset time and peak time of the CIVD was best for the first wave of temperature increase. Tail temperatures prior to immersion indicated vasodilatation when the rat rested at chamber temperatures of 28 °C or above, vasoconstriction when the chamber was kept at 24 °C or lower. The number of rats showing CIVD decreased with decreasing ambient temperatures below 32 °C.

Thermoregulatory responses during competitive marathon running

1977 ◽  
Vol 42 (6) ◽  
pp. 909-914 ◽  
Author(s):  
M. B. Maron ◽  
J. A. Wagner ◽  
S. M. Horvath
Keyword(s):  
Skin Temperature ◽  
Marathon Running ◽  
Heat Illness ◽  
Mean Skin Temperature ◽  
Total Water ◽  
Water Losses ◽  
Thermoregulatory Responses ◽  
Marked Disparity ◽  
Skin Temperatures ◽  
Cool Conditions

To assess thermoregulatory responses occuring under actual marathon racing conditions, rectal (Tre) and five skin temperatures were measured in two runners approximately every 9 min of a competitive marathon run under cool conditions. Race times and total water losses were: runner 1 = 162.7 min, 3.02 kg; runner 2 = 164.6 min, 2.43 kg. Mean skin temperature was similar throughout the race in the two runners, although they exhibited a marked disparity in temperature at individual skin sites. Tre plateaued after 35--45 min (runner 1 = 40.0--40.1, runner 2 = 38.9--39.2 degrees C). While runner 2 maintained a relatively constant level for the remainder of the race, runner 1 exhibited a secondary increase in Tre. Between 113 and 119 min there was a precipitous rise in Tre from 40.9 to 41.9 degrees C. Partitional calorimetric calculations suggested that a decrease in sweating was responsible for this increment. However, runner 1's ability to maintain his high Tre and running pace for the remaining 44 min of the race and exhibit no signs of heat illness indicated thermoregulation was intact.

Comparative Efficacy of Physiological Responses and Skin Temperatures in Indigenous and Crossbred Cattle Supplemented with Chlorophytum borivilianum in Summer Season

2021 ◽  
Author(s):  
Pooja Devi ◽  
Mahendra Singh ◽  
Yallappa M. Somagond ◽  
A.K. Roy
Keyword(s):  
Heat Stress ◽  
Skin Temperature ◽  
Physiological Responses ◽  
High Dose ◽  
Crossbred Cattle ◽  
Comparative Efficacy ◽  
Production Potential ◽  
Chlorophytum Borivilianum ◽  
Humidity Index ◽  
Skin Temperatures

Background: Heat stress causes oxidative stress and declines milk production potential of cows. The physiological responses and skin temperature of heat stressed animals are good indices for deterring the heat stress. The efficacy of medicinal herb Chlorophytum borivilianum (CB) was tested in lowering the rise in values of physiological responses and skin temperature in crossbred vis a vis Indigenous cows. Methods: Eighteen Tharparkar (TP) and Crossbred KF cows in mid-lactation were given; No supplement (control), a low (T1, n=6) and a high dose (T2, n=6) of CB @ 40 and 80 mg/kg BW/day, respectively for 90 days during hot-humid season. Respiration rate (RR), pulse rate (PR), rectal temperature (RT) and skin temperature (ST) was recorded at the site of forehead, neck, rear body, and udder surface in the morning and afternoon at weekly intervals. Temperature-humidity index (THI) was calculated to assess the degree of thermal stress in animals. Result: Physiological responses and skin temperatures were higher (p less than 0.01) in the afternoon than morning intervals in TP and KF cows. CB feeding significantly lowered physiological responses and ST (p less than 0.01) in high dose as compared to low dose. It was concluded that CB feeding @ 80 mg/kg BW/day effectively alleviates the heat stress. Indigenous cows were found more heat tolerant in comparison to crossbred cows.

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