Hypergravic fields and parallel controllers for thermoregulation

1983 ◽  
Vol 55 (3) ◽  
pp. 990-995 ◽  
Author(s):  
C. B. Monson ◽  
J. M. Horowitz ◽  
B. A. Horwitz
Keyword(s):  
Oxygen Consumption ◽  
Cold Exposure ◽  
Temperature Regulation ◽  
Room Temperature ◽  
Male Rats ◽  
Nonshivering Thermogenesis ◽  
Long Evans

To test the proposal that mammals have parallel neurocontrollers for temperature regulation, Long-Evans hooded male rats were exposed to cold while in a 3-G field. When exposed to cold, these rats consumed 35% less oxygen/min at 3 G than they did when exposed to cold at 1 G. However, rats acclimated for 6 wk to 5 degrees C consumed oxygen at the same rate during cold exposure at 3 G as at 1 G. Because cold-acclimated rats generate heat primarily by nonshivering thermogenesis while rats acclimated to room temperature rely to a greater extent on shivering, the 35% decrease in oxygen consumption of cold-exposed room-temperature rats in 3-G fields may reflect an inactivation of shivering. These oxygen consumption measurements, together with measurements of core and tail temperatures of rats in 3-G fields, are consistent with the proposal that neurocontrollers for thermoregulation are arranged in parallel and can be uncoupled by hypergravic fields.

Responses of cold- and warm-adapted dogs to infused norepinephrine and acute body cooling

1965 ◽  
Vol 209 (1) ◽  
pp. 227-230 ◽  
Author(s):  
Tetsuo Nagasaka ◽  
Loren D. Carlson
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Cold Exposure ◽  
Nonshivering Thermogenesis ◽  
Mechanically Ventilated ◽  
Cold Adapted ◽  
Pentobarbital Sodium ◽  
Acute Cold Exposure ◽  
Increased Sensitivity ◽  
Body Cooling

Oxygen consumption, heart rate, and colonic, pinna, and paw temperatures were recorded continuously in warm-adapted (W-A) and cold-adapted (C-A) dogs anesthetized with pentobarbital sodium (30 mg/kg), paralyzed with Flaxedil (5 mg/kg per hr), and mechanically ventilated. The dogs were infused with norepinephrine (1.25 µg/kg per min) for 20 min at 30 C and after 45 min of acute cold exposure to 5 C. Oxygen consumption of C-A dogs increased with a slight increase in the heart rate during the initial 18–20 min of body cooling. O2 consumption decreased continuously during cold exposure in W-A dogs. Calorigenic effects of infused noradrenaline were similar in C-A and W-A dogs at 30 C and 5 C. Heart rate increased in W-A dogs at 30 and 5 C. These results show that nonshivering thermogenesis is well developed by cold acclimation in dogs, and suggest that the increase may be due to an increase in noradrenaline in blood rather than to increased sensitivity of the animals to the calorigenic effects of noradrenaline.

Effect of age and gender on thermoregulation

1989 ◽  
Vol 257 (4) ◽  
pp. R700-R704 ◽  
Author(s):  
R. B. McDonald ◽  
C. Day ◽  
K. Carlson ◽  
J. S. Stern ◽  
B. A. Horwitz
Keyword(s):  
Oxygen Consumption ◽  
Cold Exposure ◽  
Female Rats ◽  
Male Rats ◽  
Differential Heat ◽  
Independent Basis ◽  
Male And Female Rats ◽  
Brown Adipose ◽  
And Gender ◽  
Colonic Temperature

Previous investigations have shown that during cold exposure 24-mo-old male Fischer 344 (F344) rats do not thermoregulate as well as do 12-mo-old animals. To determine if this deficiency also occurs in female rats, we measured oxygen consumption (thermogenesis) and colonic temperature of male and female rats 5, 23, and 27 mo of age at rest and during 6 h of exposure to 6 degrees C. In addition, nonshivering thermogenesis (NST) was evaluated from the capacity of brown adipose tissue (BAT) mitochondria isolated from cold-exposed rats to bind guanosine 5'-diphosphate (GDP). Neither age nor gender had a significant effect on resting or cold-exposed oxygen consumption expressed on a mass-independent basis (l/kg body mass0.67) or on a lean body mass independent basis (l/kg lean body mass0.67). The drop in colonic temperature in response to cold was greater in the male rats. However, females exhibited increased BAT mass and relatively constant GDP binding with advancing age, whereas males showed decreased mass and GDP binding. Although the data suggest greater NST capacity in the female rats, rates of cold-induced oxygen consumption were similar in older female vs. male rats. Taken together, our data indicate that gender has a significant impact on thermoregulation and that, under the cold exposure conditions of the study, this effect involves differential heat conservation rather than heat production.

Responses of cold-acclimatized men to infused norepinephrine

1963 ◽  
Vol 18 (6) ◽  
pp. 1209-1212 ◽  
Author(s):  
Robert J. T. Joy
Keyword(s):  
Oxygen Consumption ◽  
Cold Exposure ◽  
Nonshivering Thermogenesis ◽  
Drug Induced ◽  
Cold Acclimatization ◽  
Heart Rates ◽  
Before And After ◽  
Blood Pressures ◽  
Skin Temperatures ◽  
Healthy Males

Nine healthy males were infused with norepinephrine (o. μg/kg min) for 20 min before and after five 40-hr weeks of seminude exposure to 5 C. All infusions were given in the basal state, in a quiet room at 27 C, after a 30-min period of control measurements. Rectal temperatures and respiratory rates were unchanged either by the drug or the intervening cold exposure. The drug increased respiratory minute volumes and tidal volumes and decreased heart rates, but equally so in both experiments. Mean skin temperatures were unaffected by the drug but were significantly (P < .025) higher after cold exposure (mean 1 C). Both basal and drug-induced increase above basal of systolic and diastolic blood pressures was significantly lower (P < .025) after cold exposure. Oxygen consumption was the same in both basal periods and was unaffected by the drug before cold exposure. After cold exposure, norepinephrine produced a significant (P < .025) increase in oxygen consumption (mean 18 cc/min m2). These results show a changed sensitivity to norepinephrine in cold-exposed men, with a decrease in vasopressor response and the development of a calorigenic response. The data suggest that in men, norepinephrine may be a mediator of a nonshivering thermogenesis occurring with cold acclimatization. Note: (With the Assistance of Joseph C. Matone, Gerald W. Newcomb, and Wendell C. Bradford) cold exposure; catecholamines; norepinephrine calorigenesis; nonshivering thermogenesis Submitted on May 2, 1963

Effects of Castration, Testosterone Propionate and Exposure to Cold on the Oxygen Uptake of Rat Tissues

1956 ◽  
Vol 186 (3) ◽  
pp. 471-474 ◽  
Author(s):  
M. E. Denison ◽  
R. L. Jasper ◽  
W. A. Hiestand ◽  
M. X. Zarrow
Keyword(s):  
Oxygen Uptake ◽  
Cold Exposure ◽  
Room Temperature ◽  
Testosterone Propionate ◽  
Brain Slices ◽  
Sesame Oil ◽  
Male Rats ◽  
Rat Tissues ◽  
Tissue Slices ◽  
Exposure To Cold

Oxygen uptake of liver, kidney and brain slices was determined from intact and castrated male rats exposed to cold (2 ± 2°C) and treated with either testosterone propionate or sesame oil. Rats were treated with 1 mg testosterone propionate or 0.1 cc sesame oil daily for periods of 15 and 50 days. Another group of intact and castrated rats were maintained at room temperature (23 ± 2°C) and treated similarly to the animals exposed to cold. The oxygen uptake of the tissue slices was compared to that observed in tissue slices from control rats receiving no treatment. Castration caused an increase in oxygen uptake and treatment with testosterone propionate caused a decrease. Treatment of intact and castrated rats with testosterone propionate during cold exposure resulted in increased oxygen uptake. Sesame oil alone, likewise, resulted in increased oxygen uptake of liver and brain slices from castrated rats treated during cold exposure. The oxygen uptake of kidney slices from castrated rats was not affected by exposure to cold.

Cellular proliferation and UCP content in brown adipose tissue of cold-exposed aging Fischer 344 rats

1998 ◽  
Vol 274 (1) ◽  
pp. R196-R203 ◽  
Author(s):  
Maria Florez-Duquet ◽  
Barbara A. Horwitz ◽  
Roger B. McDonald
Keyword(s):  
Cell Proliferation ◽  
Cold Exposure ◽  
Fold Increase ◽  
Brown Fat ◽  
Male Rats ◽  
Nonshivering Thermogenesis ◽  
Fischer 344 ◽  
Brown Adipose ◽  
Igf I ◽  
Old Rats

Previous investigations have demonstrated that older vs. younger rats respond to cold exposure with blunted cold-induced nonshivering thermogenesis of brown adipose tissue (BAT). This reduction in nonshivering thermogenesis is associated with reduced mass and blunted nonshivering thermogenic capacity of BAT. The purpose of this study was to test the hypothesis that brown fat in 26-mo-old Fischer 344 (F344) male rats has an impaired capacity to respond to the trophic stimulus of chronic cold exposure with increases in cell number, mass, and uncoupling protein (UCP) content. To test this hypothesis, the response of BAT to chronic cold exposure was evaluated in young and old rats. We exposed 6-, 12-, and 26-mo-old F344 male rats to 10°C for 5 days and measured interscapular BAT (IBAT) mass, cell size and proliferation, and mitochondrial UCP1 content. Plasma concentrations of insulin-like growth factor I (IGF-I) and norepinephrine (NE) were also determined. The 26-mo-old rats did not increase IBAT mass, cell proliferation, or UCP1 content in response to chronic cold, whereas the 6-mo-old rats had a nearly 2-fold cold-induced increase in IBAT mass, a 26-fold increase in cell proliferation, and a 4-fold increase in UCP1 content. Cold exposure also produced an increase of 29, 19, and 20% in mature brown adipocyte cell size of the 6-, 12-, and 26-mo-old animals, respectively. Plasma levels of IGF-I were unaffected by cold at all ages, whereas NE levels were increased by the cold exposure and by increasing age. These data support the hypothesis that brown fat in old F344 rats does not respond to the trophic stimulus of chronic cold exposure to the same degree as younger animals. Moreover, these data indicate that the observed cold- or age-induced changes in levels of growth factors evaluated in this study were not associated with the lack of cold-induced preadipocyte proliferation or increased UCP1 in brown fat of the 26-mo-old rats.

OXYGEN SUPPLY AND PERFORMANCE IN PEROMYSCUS: COMPARISON OF EXERCISE WITH COLD EXPOSURE

1967 ◽  
Vol 45 (3) ◽  
pp. 543-549 ◽  
Author(s):  
Neri P. Segrem ◽  
J. S. Hart
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Body Temperature ◽  
Oxygen Uptake ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Cold Exposure ◽  
Temperature Regulation ◽  
Oxygen Supply ◽  
And Performance

Oxygen consumption, heart rate, and body temperature were measured at temperatures ranging from 27 °C to −28 °C and at oxygen partial pressure [Formula: see text] levels from 60 to 196 mm Hg. Temperature regulation and O2 uptake were progressively limited by reduction of [Formula: see text]. Limitation of O2 consumption by O2 supply was similar to that seen during exercise. The highest oxygen uptake during exposure to cold was greater than during exercise at the higher levels of [Formula: see text].

Chamber cold acclimatization in man

1961 ◽  
Vol 16 (6) ◽  
pp. 1011-1015 ◽  
Author(s):  
Thomas R. A. Davis
Keyword(s):  
Oxygen Consumption ◽  
Air Temperature ◽  
Rectal Temperature ◽  
Heat Production ◽  
Cold Exposure ◽  
Technical Assistance ◽  
Exposure Period ◽  
Seasonal Difference ◽  
Nonshivering Thermogenesis ◽  
Cold Acclimatization

In March, ten nude subjects were exposed 8 hr daily for 31 days to an air temperature of 11.8 C. In September, another six subjects were similarly acclimatized to an air temperature of 13.5 C. Measurements were made of the responses of shivering, oxygen consumption, rectal temperature, and skin temperature to a standard cold exposure. By the 14th day, shivering in both groups decreased significantly. Heat production remained unchanged in the winter group but decreased in the summer group. Basal metabolism did not change in either group. In both groups, rectal temperatures were maintained at lower values after the exposure period. In the winter group extremity temperatures were unchanged; those in the summer group were lowered by a small amount. The decrease in heat production and mean surface temperature in the summer group is related to the seasonal difference in cold acclimatization. Failure of cold-elevated metabolism to decrease despite a highly significant decrease in shivering indicates the presence of nonshivering thermogenesis in man. It is concluded that man can be artificially cold acclimatized. Note: With the Technical Assistance of D. R. Johnston, F. C. Bell, W. Rawlings, and L. Lee Submitted on May 8, 1961

Effects of exposure to 5°C and advancing age on tissue mast cells and heparin in male rats

1960 ◽  
Vol 198 (1) ◽  
pp. 180-182 ◽  
Author(s):  
L. Marx ◽  
M. Hirota ◽  
C. A. Printup ◽  
M. A. Warnick ◽  
W. Marx
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Cold Exposure ◽  
Room Temperature ◽  
Age Groups ◽  
Male Rats ◽  
Clotting Time ◽  
External Temperature ◽  
Cell Counts ◽  
Two Age Groups

Mast cell counts and heparin concentrations in liver, lung, kidney, thymus and spleen, and serum heparin levels and blood clotting times were determined in two age groups of male rats, exposed to 5°C for 1 week, and in controls of the same ages kept at room temperature. It was observed that the mast cell counts from different regions of the same organ were similar. With advancing age, the mast cells became more numerous in lung and thymus and, to a lesser degree, in kidney. Cold exposure caused an elevation of the mast cell numbers in the younger group but a depression in the older animals; these changes were significant in lung and thymus. The heparin content of thymus rose with advancing age; a similar trend was seen in lung. Cold exposure had no effect on tissue heparin levels. The serum concentration of the anticoagulant was not influenced by age or external temperature, but the clotting time was elevated by both advancing age and cold environment.

Effects of thyroid hormones on mitochondrial oxygen consumption in brown adipose tissue and heart from cold-exposed hypothyroid rats

1992 ◽  
Vol 127 (1) ◽  
pp. 72-75 ◽  
Author(s):  
LF Cageao ◽  
IR Mignone ◽  
CR Ricci ◽  
CC Brignone ◽  
JA Brignone ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Oxygen Consumption ◽  
Brown Adipose Tissue ◽  
Cold Exposure ◽  
Room Temperature ◽  
Treated Group ◽  
Maximal Response ◽  
Mitochondrial Oxygen Consumption ◽  
Iopanoic Acid ◽  
Brown Adipose

The present work measured brown adipose tissue and heart mitochondrial oxygen consumption in hypothyroid rats treated with replacement doses of T3, T4 or T4 plus iopanoic acid and kept at 4°C for 24 h. Heart oxygen consumption in normal, untreated hypothyroid and T4-treated hypothyroid rats was unaffected by cold exposure. In rats treated with T4 plus iopanoic acid, rates of oxygen consumption were normal in those maintained at 4°C as well as in those kept at room temperature, despite serum T3 concentration being significantly decreased. The cold-exposed T3-treated hypothyroid rats showed a marked decrease in oxygen consumption (p<0.02) and α-glycerophosphate dehydrogenase activity, a T3-dependent enzyme. Mitochondrial oxygen consumption in brown fat from normal (p<0.01), T4-(p<0.02) and T4 plus iopanoic acid-treated (p<0.01) rats rose more than twofold in response to cold. In the T3-treated group, oxygen consumption at room temperature was higher (p<0.02) than in any other group at similar temperatures. However, the T3-treated group showed no changes in oxygen consumption in response to cold, perhaps because this group reached the maximal response at room temperature. The untreated and the T3-treated hypothyroid rats (both groups devoid of T4) did not survive at 4°C unless T4 or several-fold replacement amounts of T3 were administered. The data demonstrate the crucial role of T4 in thermogenesis during cold exposure.

THE ANDROGENIC RESPONSE OF THE GENITAL ACCESSORY ORGANS OF THYROXINE-TREATED AND CASTRATED RATS EXPOSED TO COLD

1971 ◽  
Vol 49 (4) ◽  
pp. 591-598 ◽  
Author(s):  
R. P. DAS ◽  
M. J. PERRAULT
Keyword(s):  
Thyroid Hormone ◽  
Cold Exposure ◽  
Room Temperature ◽  
Testosterone Propionate ◽  
Male Rats ◽  
Exposure To Cold

SUMMARY The role of the thyroid in cold-induced atrophy of the genital accessory organs and the protection by treatment with testosterone against such atrophy have been evaluated in intact and castrated male rats. Treatment with thyroxine or exposure to cold reduced the weight and some of the activities of the genital accessory organs in intact but not in castrated rats. Testosterone propionate implants not only protected these organs from the cold-induced atrophy but also stimulated them beyond the level of intact controls kept at room temperature. The weight and some functions of the genital accessory organs of testosterone-treated castrated rats were decreased after cold exposure. These changes were more pronounced when thyroxine was administered simultaneously. The results suggest that the cold-induced atrophy of the accessory organs is due to the release of excess thyroid hormone and that implants of testosterone propionate can prevent this atrophy.

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