Regulation of shivering and nonshivering heat production during acclimation of rats

1960 ◽  
Vol 198 (3) ◽  
pp. 471-475 ◽  
Author(s):  
T. R. A. Davis ◽  
D. R. Johnston ◽  
F. C. Bell ◽  
B. J. Cremer
Keyword(s):  
Oxygen Consumption ◽  
Heat Source ◽  
Skin Temperature ◽  
Core Temperature ◽  
Heat Production ◽  
Cold Exposure ◽  
Central Temperature ◽  
Early Stages

When cold acclimating rats are treated with diathermy, curare and a combination of both, two main fractions of the increase in cold-induced oxygen consumption can be delineated. First, a fraction which diathermy replaces by virtue of the fact that it, in the intensities used, can raise core temperature without altering the temperature of the skin; therefore this fraction appears to be dependent upon changes in central temperature and is found to persist throughout the period of acclimation investigated. Second, a fraction of cold-induced oxygen consumption which is not replaced by diathermy and which is presumed to be dependent upon changes in skin temperature. By the administration of curare, this second fraction can be separated into two further fractions acting reciprocally depending upon the duration of cold exposure. In the early stages of acclimation, the curare-suppressed fraction of oxygen consumption appears to be entirely due to shivering. As shivering disappears with acclimation, it is replaced by a peripherally regulated nonshivering heat source which eventually takes over all the duties of heat production previously performed by shivering.

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.

Thermal balance and biogenic amine excretion in Gaspé fishermen exposed to cold

1964 ◽  
Vol 19 (1) ◽  
pp. 9-12 ◽  
Author(s):  
Jacques Leblanc ◽  
M. Pouliot ◽  
S. Rheaume
Keyword(s):  
Body Temperature ◽  
Cold Stress ◽  
Skin Temperature ◽  
Biogenic Amine ◽  
Heat Production ◽  
Cold Exposure ◽  
Technical Assistance ◽  
Control Group ◽  
Catecholamine Excretion ◽  
Adrenergic Response

Previous studies have shown a decreased response in fishermen to cold applied locally. In the present study, the same subjects, when exposed naked for 1 hr at 60 F maintained a higher skin temperature than a control group. If these findings indicate a decreased vasoconstriction, all results obtained to date on these fishermen would indicate a decreased adrenergic response. Evidence of gross shivering was much more pronounced in the fishermen but this was not reflected by greater heat production. Both groups excreted more hydroxycortisone in the cold, and the excretion was higher in the control subjects. Cold exposure did not increase the catecholamine excretion in either group. Note: (With the Technical Assistance of P. Tousignant) acclimatization; body temperature; skin temperature; vasomotor adaptation; shivering; adrenergic response in cold habituation; hydroxycortisone excretion in cold stress Submitted on June 17, 1963

Reduced stress- and cold-induced increase in energy expenditure in interleukin-6-deficient mice

2006 ◽  
Vol 291 (3) ◽  
pp. R551-R557 ◽  
Author(s):  
Ingrid Wernstedt ◽  
Amanda Edgley ◽  
Anna Berndtsson ◽  
Jenny Fäldt ◽  
Göran Bergström ◽  
...  
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Energy Expenditure ◽  
Core Temperature ◽  
Cold Exposure ◽  
Interleukin 6 ◽  
Utilization Rate ◽  
Sympathetic Outflow ◽  
Wild Type ◽  
Deficient Mice

Interleukin-6 (IL-6) deficient (-/-) mice develop mature onset obesity. Pharmacological studies have shown that IL-6 has direct lipolytic effects and when administered centrally increases sympathetic outflow. However, the metabolic functions of endogenous IL-6 are not fully elucidated. We aimed to investigate the effect of IL-6 deficiency with respect to cold exposure and cage-switch stress, that is, situations that normally increase sympathetic outflow. Energy metabolism, core temperature, heart rate, and activity were investigated in young preobese IL-6−/− mice by indirect calorimetry together with telemetry. Baseline measurements and the effect of cage-switch stress were investigated at thermoneutrality (30°C) and at room temperature (20°C). The effect of cold exposure was investigated at 4°C. At 30°C, the basal core temperature was 0.6 ± 0.24°C lower in IL-6−/− compared with wild-type mice, whereas the oxygen consumption did not differ significantly. The respiratory exchange ratio at 20°C was significantly higher and the calculated fat utilization rate was lower in IL-6−/− mice. In response to cage-switch stress, the increase in oxygen consumption at both 30 and 20°C was lower in IL-6−/− than in wild-type mice. The increase in heart rate was lower in IL-6−/− mice at 30°C. At 4°C, both the oxygen consumption and core temperature were lower in IL-6−/− compared with wild-type mice, suggesting a lower cold-induced thermogenesis in IL-6−/− mice. The present results indicate that endogenous IL-6 is of importance for stress- and cold-induced energy expenditure in mice.

No dynamic effector responses to fast changes of core temperature at constant skin temperature

1987 ◽  
Vol 65 (6) ◽  
pp. 1339-1346 ◽  
Author(s):  
Ulrike Roos ◽  
Claus Jessen
Keyword(s):  
Skin Temperature ◽  
Heat Loss ◽  
Core Temperature ◽  
Heat Production ◽  
Control Level ◽  
Time Derivative ◽  
Rate Of Change ◽  
Dynamic Responses ◽  
Evaporative Heat Loss ◽  
Blood Temperature

Experiments in conscious goats were done to see whether heat production and respiratory evaporative heat loss show dynamic responses to changing core temperature at constant skin temperature. Core temperature was altered by external heat exchangers acting on blood temperature, while skin temperature was maintained constant by immersing the animals up to the neck in a rapidly circulating water bath. Core temperature was altered at various rates up to 0.9 °C/min. Step deviations of core temperature from control values were always followed by a positive time derivative of effector response, but never by a negative time derivative during sustained displacement of core temperature. Ramp experiments showed that the slopes at which heat production or heat loss rose with core temperature deviating from its control level grew smaller at higher rates of change of core temperature. It is concluded that neither heat production nor respiratory evaporative heat loss respond to the rate of change of core temperature. At constant skin temperature, thermoregulatory effector responses appear to be proportional to the degree to which core temperature deviates from its set level.

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

Hypoglycaemia, Hypothermia and Shivering in Man

1981 ◽  
Vol 61 (4) ◽  
pp. 463-469 ◽  
Author(s):  
E. A. M. Gale ◽  
T. Bennett ◽  
J. Hilary Green ◽  
I. A. MacDonald
Keyword(s):  
Skin Temperature ◽  
Core Temperature ◽  
Heat Production ◽  
Plasma Glucose ◽  
Room Temperature ◽  
Insulin Infusion ◽  
Central Body ◽  
Cool Environment ◽  
Peripheral Vasodilatation ◽  
Male Subjects

1. The present experiments were designed to elucidate the reasons for the fall in central body temperature during hypoglycaemia. 2. The first experiment was carried out at a room temperature of 25 °C on 11 male subjects. Hypoglycaemia was induced by infusion of insulin. Heat production (calculated from respiratory gas exchange) rose from a baseline of 5.10 ± 0.13 kJ/min (mean ± sem) to a peak of 6.25 ± 0.21 kJ/min (P < 0.001), but core temperature fell concurrently by 0.51 ± 0.08°C and skin temperature fell by 1.1 ± 0.2°C. The net heat loss was due to peripheral vasodilatation and sweating. 3. To determine the effect of insulin-induced hypoglycaemia on thermoregulation in a cool environment, the experiment was repeated at a room temperature of 18–19°C on five of the subjects who had air blown over them until shivering was sustained. During this time heat production rose to 10.13 ± 1.67 kJ/min, but core temperature remained constant. Shivering stopped as plasma glucose fell below 2.5 mmol/l during insulin infusion and the subjects said they no longer felt cold. 4. During hypoglycaemia in the cold peripheral vasodilatation and sweating occurred, skin temperature fell by up to 0.8°C and core temperature fell below 35°C, so subjects had to be rewarmed. 5. Recovery of plasma glucose after hypoglycaemia in the cold was impaired at low body temperatures, but shivering was restored within seconds when glucose was given intravenously.

Evaluation of physiological and psychophysical strain of security guards wearing stab-resistant body armor under a simulated patrol condition

2021 ◽  
pp. 004051752110066
Author(s):  
Jie Yang ◽  
Qiqi An ◽  
Yuchen Wei ◽  
Mengqi Yuan
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Skin Temperature ◽  
Core Temperature ◽  
Heat Storage ◽  
Body Armor ◽  
Sweat Loss ◽  
Security Guards ◽  
Significant Difference ◽  
Body Heat

This study aimed to determine the effects of stab-resistant body armor (SRBA) on the physiological and psychophysical strain of security guards. Ten volunteers performed a 50-min treadmill walk at 7.0 km/h in a climate chamber where the ambient temperature and relative humidity were controlled to 40 °C and 40%, respectively. All the participants performed the walk under two experimental conditions: wearing a uniform without (CON) and with armor (SRBA). Several physiological responses (core temperature, skin temperature, heart rate, and oxygen consumption) and psychophysical parameters (thermal sensation vote, thermal comfort vote, ratings of perceived exertion, and clothing and skin wetness) were recorded during the trials. Furthermore, the sweat loss, body heat storage, and physiological strain index (PSI) were calculated based on the measurements. The results indicated no significant difference between the SRBA and CON groups in terms of core temperature, mean skin temperature, heart rate, oxygen consumption, body heat storage, or PSI over time. However, a significant difference ( p < 0.05) between the two trials was observed in terms of scapula skin temperature (40 and 45 min) and body temperature (0 and 45 min). Moreover, the SRBA (3.5 kg and 17% body area coverage) caused an 11% increase in sweat loss, but a 27% reduction in sweating efficiency. Although the armor caused slight discomfort, wetness, and exertion, no significant difference between the two trials was observed in terms of the psychophysical responses. Therefore, the SRBA imposed negligible physiological and psychophysical strain during the 50-min walk in this case.

scholarly journals Seven days of cold acclimation substantially reduces shivering intensity and increases nonshivering thermogenesis in adult humans

2019 ◽  
Vol 126 (6) ◽  
pp. 1598-1606 ◽  
Author(s):  
Kyle Gordon ◽  
Denis P. Blondin ◽  
Brian J. Friesen ◽  
Hans Christian Tingelstad ◽  
Glen P. Kenny ◽  
...  
Keyword(s):  
Cold Acclimation ◽  
Core Temperature ◽  
Heat Production ◽  
Cold Exposure ◽  
Cold Water ◽  
Water Immersion ◽  
Cold Water Immersion ◽  
Metabolic Changes ◽  
Whole Body ◽  
Nonshivering Thermogenesis

Daily compensable cold exposure in humans reduces shivering by ~20% without changing total heat production, partly by increasing brown adipose tissue thermogenic capacity and activity. Although acclimation and acclimatization studies have long suggested that daily reductions in core temperature are essential to elicit significant metabolic changes in response to repeated cold exposure, this has never directly been demonstrated. The aim of the present study is to determine whether daily cold-water immersion, resulting in a significant fall in core temperature, can further reduce shivering intensity during mild acute cold exposure. Seven men underwent 1 h of daily cold-water immersion (14°C) for seven consecutive days. Immediately before and following the acclimation protocol, participants underwent a mild cold exposure using a novel skin temperature clamping cold exposure protocol to elicit the same thermogenic rate between trials. Metabolic heat production, shivering intensity, muscle recruitment pattern, and thermal sensation were measured throughout these experimental sessions. Uncompensable cold acclimation reduced total shivering intensity by 36% ( P = 0.003), without affecting whole body heat production, double what was previously shown from a 4-wk mild acclimation. This implies that nonshivering thermogenesis increased to supplement the reduction in the thermogenic contribution of shivering. As fuel selection did not change following the 7-day cold acclimation, we suggest that the nonshivering mechanism recruited must rely on a similar fuel mixture to produce this heat. The more significant reductions in shivering intensity compared with a longer mild cold acclimation suggest important differential metabolic responses, resulting from an uncompensable compared with compensable cold acclimation. NEW & NOTEWORTHY Several decades of research have been dedicated to reducing the presence of shivering during cold exposure. The present study aims to determine whether as little as seven consecutive days of cold-water immersion is sufficient to reduce shivering and increase nonshivering thermogenesis. We provide evidence that whole body nonshivering thermogenesis can be increased to offset a reduction in shivering activity to maintain endogenous heat production. This demonstrates that short, but intense cold stimulation can elicit rapid metabolic changes in humans, thereby improving our comfort and ability to perform various motor tasks in the cold. Further research is required to determine the nonshivering processes that are upregulated within this short time period.

Cardiac sarcoplasmic reticulum Ca2+-ATPase: heat production and phospholamban alterations promoted by cold exposure and thyroid hormone

2009 ◽  
Vol 297 (2) ◽  
pp. H556-H563 ◽  
Author(s):  
Luisa A. Ketzer ◽  
Ana Paula Arruda ◽  
Denise P. Carvalho ◽  
Leopoldo de Meis
Keyword(s):  
Oxygen Consumption ◽  
Sarcoplasmic Reticulum ◽  
Heat Production ◽  
Cold Exposure ◽  
Mitochondrial Respiration ◽  
Significant Rise ◽  
Short Term ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Serum T3 ◽  
Term Response

Short-term response to cold promotes a small but significant rise in serum T3 in euthyroid rabbits, where the heart is an important target of T3 action. In this work, we measured changes in sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA2a) and phospholamban (PLB) in hearts of hypo- and hyperthyroid rabbits and compared them with modifications induced by short- and long-term cold exposure. Short-term cold exposure promotes a small increase in T3 and, similar to hyperthyroidism, induces an increase of heart SERCA2a expression. The total PLB content does not change in hyperthyroidism, but short-term cold exposure promotes a significant decrease in total PLB and an increase in the ratio between phosphorylated and total PLB. The temperature of a given tissue depends on the balance between the heat provided by blood circulation and the rate of heat production by the tissue. In an attempt to evaluate the heat contribution of cardiac tissue, we measured mitochondrial respiration in permeabilized cardiac muscle and heat produced by cardiac sarcoplasmic reticulum (SR) during Ca2+ transport. We observed that there was an increase in oxygen consumption and heat production during Ca2+ transport by cardiac SR in both hyperthyroidism and short-term cold exposure. In contrast, both the mitochondrial respiration rate and heat derived from Ca2+ transport were decreased in hypothyroid rabbits. The heart changes in oxygen consumption, SERCA2a-PLB ratio, and Ca2+-ATPase activity detected during short-term cold exposure were abolished after cold adaptation. We hypothesize that the transient rise in serum T3 contributes to the short-term response to cold exposure.

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