SEASONAL CHANGES IN THE PHYSIOLOGICAL RESPONSE OF MAN TO AN ACUTE COLD STRESS

1967 ◽  
Vol 45 (1) ◽  
pp. 13-27 ◽  
Author(s):  
F. Girling
Keyword(s):  
Cold Stress ◽  
Heat Production ◽  
Cold Exposure ◽  
Seasonal Changes ◽  
Human Subjects ◽  
Minute Ventilation ◽  
Acute Cold Exposure ◽  
Air Temperatures ◽  
The Individual ◽  
Shivering Thermogenesis

Eight male human subjects, resting supine, and wearing swim trunks only, were exposed to an ambient temperature of 8.5 °C for 1 hour in the first week of each month from February 1964 to January 1965 inclusive. Skin, rectal, and air temperatures were measured with thermistor probes. Percentage oxygen in expired air and minute ventilation were measured, and heat production was calculated by Weir's method. Electrical activity from the muscles of all four limbs was measured to determine shivering response. Control values of resting respiration and heat production were obtained under comfortably warm conditions and showed marked seasonal variation, with minimum values in spring and maximum values in later summer. In the response to acute cold exposure, marked seasonal changes were found also which were superimposed on the seasonal changes in control values. The response to cold exposure indicated maximum acclimatization to cold in the spring and minimum in later summer. These results are discussed in terms of three modes of response to the cold stress: (i) insulative cooling, (ii) shivering thermogenesis, and (iii) nonshivering thermogenesis. The degree of acclimatization and temperature of exposure may determine the individual mode of response.

Physical fitness and thermoregulatory reactions in a cold environment in men

1988 ◽  
Vol 65 (5) ◽  
pp. 1984-1989 ◽  
Author(s):  
J. H. Bittel ◽  
C. Nonotte-Varly ◽  
G. H. Livecchi-Gonnot ◽  
G. L. Savourey ◽  
A. M. Hanniquet
Keyword(s):  
Physical Fitness ◽  
Cold Stress ◽  
Heat Production ◽  
Ambient Air ◽  
Metabolic Heat Production ◽  
Adult Males ◽  
Fitness Level ◽  
Metabolic Heat ◽  
Air Temperatures ◽  
Thermoregulatory Reactions

The relationship between the physical fitness level (maximal O2 consumption, VO2max) and thermoregulatory reactions was studied in 17 adult males submitted to an acute cold exposure. Standard cold tests were performed in nude subjects, lying for 2 h in a climatic chamber at three ambient air temperatures (10, 5, and 1 degrees C). The level of physical fitness conditioned the intensity of thermoregulatory reactions to cold. For all subjects, there was a direct relationship between physical fitness and 1) metabolic heat production, 2) level of mean skin temperature (Tsk), 3) level of skin conductance, and 4) level of Tsk at the onset of shivering. The predominance of thermogenic or insulative reactions depended on the intensity of the cold stress: insulative reactions were preferential at 10 degrees C, or even at 5 degrees C, whereas colder ambient temperature (1 degree C) triggered metabolic heat production abilities, which were closely related to the subject's physical fitness level. Fit subjects have more efficient thermoregulatory abilities against cold stress than unfit subjects, certainly because of an improved sensitivity of the thermoregulatory system.

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

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

Gastrointestinal motility and plasma hormone and metabolite responses to acute cold stress and somatostatin-14 in sheep

1991 ◽  
Vol 71 (4) ◽  
pp. 1079-1086 ◽  
Author(s):  
R. A. Christensen ◽  
J. J. Kennelly ◽  
R. J. Christopherson
Keyword(s):  
Gastrointestinal Motility ◽  
Cold Exposure ◽  
Average Duration ◽  
Apparent Effect ◽  
Orthogonal Contrasts ◽  
Ewe Lambs ◽  
Acute Cold Exposure ◽  
The Individual ◽  
Key Words Cold ◽  
Somatostatin 14

Effects of intrajugular infusions of somatostatin-14 (SS-14) (8.9, 18.4, and 37.3 ng min−1 kg−1 BW) or saline were studied in three acutely (2 h) cold-stressed (0 °C) ewe lambs (39.8 ± 1.8 kg BW) fed a barley soybean meal diet at 25.6 g DM d−1 kg−1 BW. Acute cold exposure transiently increased (P < 0.001) and rewarming decreased (P < 0.001) recticular contraction frequency, with no effect of SS-14. The duration of duodenal irregular spiking activity was decreased (P < 0.05) by SS-14 at doses of 18.3 and 37.3 ng min−1 kg−1 and was not affected by cold exposure. This resulted in a decrease (P < 0.05) in the average duration of the individual migrating myoelectric complex. Cold exposure increased (P < 0.01) plasma concentration of free fatty acids (FFA). Orthogonal contrasts of the changes during somatostatin infusion indicated linear increases in glucose and linear and cubic increases in FFA concentrations in plasma (P < 0.05). Infusion of somatostatin had no effect on basal concentrations of growth hormone, insulin, or glucagon but produced linear reductions in plasma insulin and glucagon responses during cold exposure (P < 0.05). Somatostatin modestly influenced hormone and metabolite concentration during acute cold exposure without apparent effect on body temperature. Key words: Cold, somatostatin, sheep, gastrointestinal motility, glucagon, insulin

scholarly journals Transcriptome Profiles of the Liver in Two Cold-Exposed Sheep Breeds Revealed Different Mechanisms and Candidate Genes for Thermogenesis

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Dan Jiao ◽  
Kaixi Ji ◽  
Wenqiang Wang ◽  
Hu Liu ◽  
Jianwei Zhou ◽  
...  
Keyword(s):  
Candidate Genes ◽  
Heat Production ◽  
Theoretical Foundation ◽  
Nonshivering Thermogenesis ◽  
Ewe Lambs ◽  
Air Temperatures ◽  
Liver Transcriptome ◽  
The Difference ◽  
Shivering Thermogenesis

Cold-induced thermogenesis plays an important role in the survival of lambs exposed to low air temperatures. The liver produces and mediates heat production in mammals; however, to date, little is known about the role of liver genes in cold-induced thermogenesis in lambs. In this study, the difference in the liver transcriptome between Altay and Hu ewe lambs was compared. Because of different backgrounds of the two breeds, we hypothesized that the transcriptome profiles of the liver would differ between breeds when exposed to cold. Cold-exposed Altay lambs activated 8 candidate genes (ACTA1, MYH1, MYH2, MYL1, MYL2, TNNC1, TNNC2, and TNNT3) involved in muscle shivering thermogenesis; 3 candidate genes (ATP2A1, SLN, and CKM) involved in muscle nonshivering thermogenesis related to the Ca2+ signal and creatine cycle; and 6 candidate genes (PFKM, ALDOC, PGAM2, ENO2, ENO3, and ENO4) involved in enhancing liver metabolism. In contrast, the liver may not act as the main tissue for thermogenesis in cold-exposed Hu lambs. We concluded that Altay lambs rely on liver-mediated shivering and nonshivering thermogenesis by muscle tissue to a greater extent than Hu lambs. Results from this study could provide a theoretical foundation for the breeding and production of cold-resistant lambs.

Shivering thermogenesis during acute hypercapnia

1994 ◽  
Vol 72 (3) ◽  
pp. 238-242 ◽  
Author(s):  
Victor Lun ◽  
John C. L. Sun ◽  
Gordon G. Giesbrecht ◽  
Igor B. Mekjavić
Keyword(s):  
Carbon Dioxide ◽  
Cold Exposure ◽  
Cold Water ◽  
Minute Ventilation ◽  
Water Immersion ◽  
Emg Activity ◽  
Gas Mixture ◽  
Electromyographic Activity ◽  
Esophageal Temperature ◽  
Shivering Thermogenesis

The effects of acute hypercapnia on human thermoregulation during cold exposure were investigated by immersion of eight male subjects to the neck in a 15 °C water bath until their core temperatures dropped to 35 °C or until 1 h of immersion had elapsed. Air was inspired throughout each experiment, with the exception of a 15-min period commencing with the attainment of an esophageal temperature (Tes) of 36.5 °C, during which subjects inspired a gas mixture containing 4% CO2, 20% O2, and 76% N2. Oxygen uptake ([Formula: see text], L∙min−1), inspired minute ventilation ([Formula: see text], L∙min−1), esophageal temperature (Tes, °C), rectal temperature (Tre, °C), mean unweighted skin temperature (Tsk, °C), mean heat flux (Q, W∙m−2), and electromyographic activity (EMG, mV) of the trapezius and masseter muscles were recorded continuously. [Formula: see text] and integrated EMG activity (IEMG) were used as the primary indicators of shivering thermogenesis. Shivering EMG was attenuated immediately following the switch of the inhaled gas mixture from air to 4% CO2. For both the massetter and trapezius muscles the IEMG was significantly suppressed (p < 0.05) during the hypercapnic period. The IEMG values preceding the switch to the hypercapnic mixture were 15% greater than those during the CO2 period. Similarly, IEMG values in the post-CO2 period were 55% greater than during the CO2 period. It is concluded that acute periods of hypercapnia during cold exposure may result in transient suppression of shivering tremor, but this does not appear to affect thermal balance, as reflected in the absence of any significant effect on Tes.Key words: temperature regulation, carbon dioxide, hypothermia, diving, cooling, cold water immersion, carbon dioxide retention.

ACUTE EXPOSURE OF HUMAN SUBJECTS TO AN AMBIENT TEMPERATURE OF 10 °C

1964 ◽  
Vol 42 (2) ◽  
pp. 233-243 ◽  
Author(s):  
D. A. Hurley ◽  
E. D. L. Topliff ◽  
F. Girling
Keyword(s):  
Oxygen Consumption ◽  
Ambient Temperature ◽  
Heat Production ◽  
Human Subjects ◽  
Healthy Male ◽  
Cold Acclimatization ◽  
Seasonal Acclimatization ◽  
Time Of Year ◽  
Male Subjects ◽  
Shivering Thermogenesis

Acute exposures to cold (10 °C) for 1 hour were carried out in early April on five unclothed healthy male subjects to follow their shivering responses, oxygen consumption, ventilation, skin and oral temperatures. Exposure to the cold resulted in immediate (within 5 minutes) and sustained increases in oxygen consumption, ventilation, and heat production. These subjects did not show generalized shivering, however, until after 30 minutes of exposure, even though short bursts of shivering were noted before this time. The immediate increase in heat production without shivering is indicative of a non-shivering thermogenesis which may be the result of cold-acclimatization in these subjects. Seasonal acclimatization would be maximal at the time of year during which the experiments were carried out.

scholarly journals Effects of green tea extracts on non-shivering thermogenesis during mild cold exposure in young men

2012 ◽  
Vol 110 (2) ◽  
pp. 282-288 ◽  
Author(s):  
Chantal Gosselin ◽  
François Haman
Keyword(s):  
Green Tea ◽  
Cold Exposure ◽  
Potential Role ◽  
Human Subjects ◽  
Exposure Period ◽  
Voluntary Contraction ◽  
Food Ingredients ◽  
Obesity And Diabetes ◽  
Shivering Thermogenesis

The effects of epigallocatechin-3-gallate (EGCG) and caffeine on non-shivering thermogenesis (NST) during cold exposure is unknown. The purpose of the present study was to quantify the effects of co-ingesting EGCG and caffeine on the thermogenic responses of a 3 h cold exposure. A total of eight healthy males were exposed to mild cold, using a liquid-conditioned suit perfused with 15°C water, on two occasions and consumed a placebo or an extract of 1600 mg of EGCG and 600 mg of caffeine (Green tea). Thermic, metabolic and electromyographic measurements were monitored at baseline and during the cold exposure. Results showed that the AUC of shivering intensity over the cold exposure period was reduced by approximately 20 % in the Green tea (266 (sem 6) % maximal voluntary contraction (MVC) × min) compared with the Placebo (332 (sem 69) %MVC × min) (P= 0·01) treatments. In contrast, the total AUC for energy expenditure (EE) was approximately 10 % higher in the Green tea (23·5 (sem 1·4) kJ/kg × 180 min) compared with the Placebo (327 (sem 74) kJ/kg 180 min) (P= 0·007) treatments. The decrease in shivering activity combined with an increase in EE, following the ingestion of EGCG and caffeine during the cold exposure, indicates that NST pathways can be significantly stimulated in adult human subjects. The present study provides an experimental approach for human investigations into the potential role of diet and bioactive food ingredients in modulating NST during cold exposure. Stimulating NST pathways in such a manner may also provide important targets in the search of targets for the management of obesity and diabetes.

Postnatal changes in regional blood flow during cold-induced shivering in sow-reared piglets

1999 ◽  
Vol 77 (6) ◽  
pp. 414-421 ◽  
Author(s):  
Gaëlle Lossec ◽  
Claude Duchamp ◽  
Yves Lebreton ◽  
Patrick Herpin
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Cardiac Output ◽  
Heat Production ◽  
Cold Exposure ◽  
Cardiovascular Response ◽  
Regional Blood Flow ◽  
Muscle Blood Flow ◽  
Cold Challenge ◽  
Shivering Thermogenesis

To determine whether newborn pigs are able to display adequate cardiovascular adjustments favouring shivering thermogenesis in skeletal muscles soon after birth, regional blood flow and fractional distribution of cardiac output were determined in 1-day-old (n = 6) and 5-day-old (n = 6) conscious piglets at thermal neutrality and during cold exposure, using coloured microspheres. Five-day-old piglets stayed with the sow before the experiment. The cold challenge was designed to induce a similar increase (~+90%) in heat production at both ages. Skeletal muscle blood flow increased with both age (p < 0.05) and cold exposure (p < 0.001), with the effect of cold being more pronounced in 5-day-old piglets than in 1-day-old piglets (+60%, p < 0.05). The difference between individual muscles increased with age, with fractional blood flow being 41% higher in rhomboideus than in longissimus thoracis muscle during cold exposure in 5-day-old piglets (p < 0.05). Cardiac output was similar at both ages and increased by 23% in the cold (p < 0.001). At 1 day of age, there was no redistribution of cardiac output among the internal organs during the cold challenge, while at 5 days of age, the increase in muscle fractional blood flow was associated with a reduction (p < 0.05) in the fraction of cardiac output reaching the skin (-24%), the small intestine (-21%), and the liver (-20%). In conclusion, these results suggest that there is a rapid postnatal improvement of cardiovascular adjustments favouring blood perfusion and probably heat production during cold-induced shivering in the most oxidative muscles studied. This cardiovascular response may play a role in the postnatal enhancement of thermoregulation in piglets.Key words: skeletal muscle, blood distribution, shivering thermogenesis, piglet, age.

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