scholarly journals Quantification of the Capacity for Cold-Induced Thermogenesis in Young Men With and Without Obesity

2019 ◽  
Vol 104 (10) ◽  
pp. 4865-4878 ◽  
Author(s):  
Robert J Brychta ◽  
Shan Huang ◽  
Juan Wang ◽  
Brooks P Leitner ◽  
Jacob D Hattenbach ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Critical Temperature ◽  
Energy Expenditure ◽  
Heat Production ◽  
Basal Metabolic Rate ◽  
Muscle Activity ◽  
Brown Fat ◽  
Nonshivering Thermogenesis ◽  
Ambient Temperatures ◽  
Lower Critical Temperature

AbstractObjectiveCold exposure increases energy expenditure (EE) and could have a role in combating obesity. To understand this potential, we determined the capacity for cold-induced thermogenesis (CIT), the EE increase above the basal metabolic rate at the individualized coldest tolerable temperature before overt shivering.DesignDuring a 13-day inpatient protocol, we quantitated the EE of 12 lean men and 9 men with obesity at various randomly ordered ambient temperatures in a room calorimeter. Subjects underwent brown fat imaging after exposure to their coldest tolerable temperature.ResultsCIT capacity was 300 ± 218 kcal/d (mean ± SD) or 17 ± 11% in lean men and 125 ± 146 kcal/d or 6 ± 7% in men with obesity (P = 0.01). The temperature below which EE increased, lower critical temperature (Tlc), was warmer in lean men than men with obesity (22.9 ± 1.2 vs 21.1 ± 1.7°C, P = 0.03), but both had similar skin temperature (Tskin) changes and coldest tolerable temperatures. Whereas lean subjects had higher brown fat activity, skeletal muscle activity increased synchronously with CIT beginning at the Tlc in both groups, indicating that muscle is recruited for CIT in parallel with brown fat, not sequentially after nonshivering thermogenesis is maximal.ConclusionsDespite greater insulation from fat, men with obesity had a narrower range of tolerable cool temperatures available for increasing EE and less capacity for CIT than lean men, likely as a result of greater basal heat production and similar perception to Tskin cooling. Further study of the reduced CIT capacity in men with obesity may inform treatment opportunities for obesity.

EFFECT OF FEED TEMPERATURE ON COLD SUSCEPTIBILITY OF CATTLE AND SHEEP

1990 ◽  
Vol 70 (1) ◽  
pp. 191-197 ◽  
Author(s):  
A. M. NICOL ◽  
B. A. YOUNG
Keyword(s):  
Critical Temperature ◽  
Heat Production ◽  
Metabolic Heat Production ◽  
Ambient Temperatures ◽  
Metabolic Heat ◽  
Lower Critical Temperature ◽  
Temperature Heat ◽  
Feed Temperature ◽  
Key Words Cold ◽  
Cattle And Sheep

The metabolic heat production of steers was measured at ambient temperatures of +10, −8 and −20 °C following their consumption of 15-kg turnip bulbs (Brassica napus) with a temperature of 27, 2 or −8 °C, or 10-kg turnips with a temperature of 2 °C followed by 1 kg hay. Metabolic heat production was elevated 13–80% after eating the cold and frozen turnips when steers were exposed to −8 °C and 35–80% when exposed to −20 °C. Sheep fed 20, 35, 55, 80 and 110 g pelleted ration per kg−0.75 d−1, accompanied by a ruminal infusion of water at 38 or 2 °C at a volume required to simulate a 10% dry matter feed had their metabolic heat production measured at +10 and −20 °C. Heat production was significantly increased at −20 °C for only the 2 °C infusion although with the 38 °C infusion at the lower feed intake levels, metabolic heat production was higher by up to 37% at an ambient temperature of −20 °C than at +10 °C. The lower critical temperature of the steers after ingestion of the turnips was estimated to be −4.5, −2.4, +3.2 and +13.9 °C forthe27, 2 + hay, 2 and −8 °C turnips, respectively. The lower critical temperature of sheep was raised by 1, 11, 31, 25 and > 22 °C by the ruminal infusion of water at 2 °C compared to water at 38 °C in sheep fed 20, 35, 55, 80 and 110 g feed kg−0.75 d−1, respectively. Key words: Cold, temperature, heat production, cattle, sheep

scholarly journals Laboratory Metabolism of Incubating Semipalmated Plovers

The Condor ◽  
2006 ◽  
Vol 108 (4) ◽  
pp. 966-970
Author(s):  
Mark Williamson ◽  
Joseph B. Williams ◽  
Erica Nol
Keyword(s):  
Critical Temperature ◽  
Metabolic Rate ◽  
Breeding Season ◽  
Basal Metabolic Rate ◽  
Low Temperatures ◽  
Thermal Conductance ◽  
Basal Metabolism ◽  
The Arctic ◽  
Lower Critical Temperature ◽  
Metabolic Data

Abstract Abstract The Semipalmated Plover (Charadriussemipalmatus), anarctic-nesting migratory shorebird, regularlyencounters low temperatures during the breedingseason. We measured the basal metabolism of adultsduring incubation at Churchill, Manitoba, Canada todetermine basal metabolic rate (BMR),lower critical temperature(Tlc), total evaporative waterloss (TEWL), and dry thermal conductance(Cm). BMR and Tlcwere 47.4 kJ day−1and 23.3°C, respectively, TEWL was2.5 mL H2O−d,and Cm was1.13 mW g−1 °C−1.Measured BMR and Tlc were consistentwith high values found for other shorebird speciesbreeding in the Arctic, while Cm was18% higher than predicted from allometricequations. These metabolic data suggest thatSemipalmated Plovers are adapted to balance therequirements of incubation against energetic andthermoregulatory demands in the Arctic, especiallyin harsh early breeding season conditions.

Increased nonshivering thermogenesis, brown fat cytochrome-c oxidase activity, GDP binding, and uncoupling protein mRNA levels after short daily cold exposure of Phodopus sungorus

1990 ◽  
Vol 68 (2) ◽  
pp. 195-200 ◽  
Author(s):  
Herbert Wiesinger ◽  
Susanne Klaus ◽  
Gerhard Heldmaier ◽  
Odette Champigny ◽  
Daniel Ricquier
Keyword(s):  
Cytochrome C Oxidase ◽  
Cold Exposure ◽  
Basal Metabolic Rate ◽  
Oxidase Activity ◽  
Uncoupling Protein ◽  
Brown Fat ◽  
Phodopus Sungorus ◽  
Mrna Levels ◽  
Nonshivering Thermogenesis ◽  
Uncoupling Protein Mrna

In their natural environment, burrowing rodents experience rather fluctuating ambient temperatures and are acutely cold exposed only for short periods outside their burrows. The effect of short daily cold exposure on basal metabolic rate, nonshivering thermogenesis, brown fat thermogenesis, and uncoupling protein mRNA was studied in the Djungarian hamster, Phodopus sungorus. They were kept at 23 °C and exposed to 5 °C daily either for one 4-h period or twice for 2 h (in 12-h intervals). At the same time control hamsters were kept continuously either at thermoneutrality (23 °C) or at 5 °C. Two 2-h cold exposures daily were sufficient to increase basal metabolic rate and nonshivering thermogenesis to the same level as continuous cold exposure, whereas one 4-h cold period per day did not result in a significant increase of both parameters. Brown fat thermogenesis (as measured by cytochrome-c oxidase activity and GDP binding to the mitochondrial uncoupling protein) increased to the same extent by both treatments with short daily cold exposure. However, this increase was less than in the chronically cold-exposed hamsters. A similar result was found for uncoupling protein mRNA: both short-term cold-exposed hamsters increased uncoupling protein mRNA levels to a similar extent, but less than after chronic cold treatment. It is concluded that short daily cold exposures are sufficient to cause adaptive increases of the capacity of metabolic heat production as well as brown fat thermogenic properties.Key words: nonshivering thermogenesis, brown fat, GDP binding, uncoupling protein mRNA, Phodopus sungorus.

Thermoregulatory heat production in cold-reared and warm-reared pigs

1983 ◽  
Vol 244 (2) ◽  
pp. R273-R278 ◽  
Author(s):  
M. Heath ◽  
D. L. Ingram
Keyword(s):  
Heat Flow ◽  
Skin Temperature ◽  
Heat Production ◽  
O2 Consumption ◽  
Nonshivering Thermogenesis ◽  
Ambient Temperatures ◽  
Ad Libitum

Pigs were reared from 2 wk of age in either 10 or 35 degrees C and fed ad libitum. At 8 wk of age they were tested for the presence of regulatory nonshivering thermogenesis by administration of norepinephrine (NE) and propranolol. In addition, an electromyogram and carotid temperature, as well as a heat flow and skin temperature from one site, were monitored while the pigs were at ambient temperatures of 10, 15, 20, 25, and 30 degrees C. Cold-reared pigs showed a heightened response to NE in cold compared to thermally neutral environments. This was not observed in warm-reared pigs. Propranolol depressed O2 consumption more in cold-reared than in warm-reared pigs. Pigs reared in the cold also showed a higher intensity of shivering, tissue conductance, and skin temperature than warm-reared littermates. The shivering response of cold-reared pigs was more sensitive to changes in skin temperature than in warm-reared pigs.

Brown fat mediates increased energy expenditure of cold-exposed overfed neonatal rats

1986 ◽  
Vol 251 (3) ◽  
pp. R518-R524
Author(s):  
B. J. Moore ◽  
J. S. Stern ◽  
B. A. Horwitz
Keyword(s):  
Energy Expenditure ◽  
Cold Exposure ◽  
Rapid Onset ◽  
Brown Fat ◽  
O2 Consumption ◽  
Neonatal Rats ◽  
Ambient Temperatures ◽  
Rat Pups ◽  
Acute Cold Exposure ◽  
Brown Adipose

Genetically lean rat pups, overfed by being raised in small litters of three from day 1 postpartum, rapidly become obese compared with pups raised in standard sized litters of eight. Because of the rapid onset of their obesity, we expected that overfed pups would exhibit defective brown fat thermogenesis as is seen in neonatal genetically obese rodents. O2 consumption (VO2) was measured in 2-, 4-, 6-, and 8-day-old homozygous lean (Fa/Fa) Zucker pups from each treatment. We determined minimum rate of VO2 at thermoneutrality and maximum VO2 in response to progressively colder ambient temperatures. Overfed pups were fatter than standard-fed pups (P less than 0.001). But contrary to our prediction, overfed pups had a significantly increased maximum VO2 in response to acute cold exposure. To test the hypothesis that brown fat mediated the increased VO2 in the overfed pups, scapular brown fat lipectomies were performed on a new group of overfed pups at 2 days of age and compared with sham-operated littermate controls. On day 8, no differences in minimum VO2 were seen at thermoneutrality when brown fat is turned off. But maximum VO2 in response to cold, when brown fat is turned on maximally, was significantly reduced in the lipectomized overfed pups compared with sham-operated overfed littermates. These data suggest that manipulations of diet, accomplished by raising pups in small litters, can increase brown fat thermogenic function. The results of the lipectomy experiment imply that brown adipose tissue is a primary mediator of the increased energy expenditure in response to acute cold exposure in the overfed pups.

Nonshivering thermogenesis in skeletal muscle of seasonally acclimatized mice, Peromyscus

1981 ◽  
Vol 241 (3) ◽  
pp. R185-R189
Author(s):  
S. J. Wickler
Keyword(s):  
Skeletal Muscle ◽  
Oxygen Consumption ◽  
Arterial Pressure ◽  
Flow Rate ◽  
Heat Production ◽  
Major Contributor ◽  
Nonshivering Thermogenesis ◽  
Perfusion System ◽  
Apparent Increase ◽  
Hindlimb Muscle

Nonshivering thermogenesis (NST) is a major contributor to total heat production capabilities of Peromyscus and the magnitude of the NST response increases dramatically in winter-acclimatized animals. To directly assess the contribution from skeletal muscle to this NST, a hindlimb perfusion system was developed for Peromyscus. Oxygen consumption was then measured with and without norepinephrine (the mediator of NST) in freshly captured animals in summer and winter. Norepinephrine (NE) was infused at 0.001, 0.01, and 0.1 micrograms . g hindlimb muscle-1 . min-1. Vascular resistance (VR), calculated as arterial pressure divided by flow rate, increased during all NE infusions. At doses of 0.001 and 0.01, VR stabilized after approximately 10 min, but at 0.1 VR continued to rise. Resting oxygen consumption was 0.817 +/- 0.037 and 0.805 +/- 0.049 mumol O2 . g-1 . min-1 in summer (n = 8) and winter (n = 7) animals, respectively. There was no apparent increase in oxygen consumption with any dosage of NE. It appears that the increase in NST in winter animals is not due to an increased NST in skeletal muscle.

Further studies on the heat production and effective lower critical temperature of early-weaned pigs under commercial conditions of feeding and management

1984 ◽  
Vol 39 (2) ◽  
pp. 283-290 ◽  
Author(s):  
K. J. McCracken ◽  
R. Gray
Keyword(s):  
Critical Temperature ◽  
Heat Production ◽  
Thermal Conductance ◽  
Open Circuit ◽  
Weaned Pigs ◽  
Respiration Chamber ◽  
Lower Critical Temperature ◽  
The Mean ◽  
The Difference ◽  
Practical Implications

ABSTRACTIn two separate experiments pigs were weaned at 14 or 28 days and heat production was determined in an open-circuit respiration chamber at temperatures above and below the lower critical temperature (Tcl) at intervals during the post-weaning period.With 14-day weaned pigs the mean 24 h heat production above Tc1 averaged 267, 328, 474 and 554 kJ/h per m2 at 3, 9, 15 and 21 days post weaning respectively. The mean thermal conductance (H/AT, kJ/h per m2 per °ΔT, where H is total heat production, m2 is the surface area calculated as 0·097 M kg0·633 and °Δ is the difference between rectal temperature, taken at 39°, and air temperature) below TC1 was calculated as 20·5, 20·1, 23·1 and 24·2 at 17, 23, 29 and 35 days of age respectively and the corresponding values for Tc1 were 25·9, 23·0, 18·4 and 16·0°C.With 28-day weaned pigs the mean 24 h heat production above Tc1 averaged 280, 361 and 445 kJ/h per m2 at 3, 9 and 15 days post weaning. The calculated values for H/ΔT were 19·7, 20·8 and 21·6 and the corresponding values of Tcl were 24·8, 21·7, and 18·8°C at 31, 37 and 43 days of age respectively.The results are discussed in relation to previous studies on 10-day and 28-day weaned pigs and in relation to the practical implications for pigs weaned into controlled-environment accommodation.

scholarly journals Muscle nonshivering thermogenesis in a feral mammal

2018 ◽  
Author(s):  
Julia Nowack ◽  
Sebastian G. Vetter ◽  
Gabrielle Stalder ◽  
Johanna Painer ◽  
Maria Kral ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Heat Production ◽  
Large Mammals ◽  
Nonshivering Thermogenesis ◽  
Ambient Conditions ◽  
Primary Mechanism ◽  
Age Related ◽  
Brown Adipose ◽  
Behavioural Adaptations ◽  
Related Increase

AbstractWhile small mammals and neonates are able to maintain an optimal body temperature (Tb) independent of ambient conditions by producing heat via nonshivering thermogenesis (NST) in the brown adipose tissue (BAT), larger mammals and other mammals lacking BAT were long believed to rely primarily on shivering and behavioural adaptations. However, recently, a second mechanism of NST was found in skeletal muscle that could play an important role in thermoregulation of such species. Muscle NST is independent of muscle contractions and produces heat based on the activity of an ATPase pump in the sarcoplasmic reticulum (SERCA1a) and controlled by the protein sarcolipin. To evaluate whether muscle NST could indeed play an important role in thermoregulation in species lacking BAT, we investigated the thermogenic capacities of new-born wild boar piglets. During cold exposure over the first 5 days of life, total heat production was improved while shivering intensity decreased, indicating an increasing contribution of NST. Sampling skeletal muscle tissue for analyses of SERCA activity as well as gene expression of SERCA1a and sarcolipin, we found an age-related increase in all three variables as well as in Tb. Hence, the improved thermogenesis during the development of wild boars is not due to shivering but explained by the observed increase in SERCA activity. Our results suggest that muscle NST may be the primary mechanism of heat production during cold stress in large mammals lacking BAT, strengthening the hypothesis that muscle NST has likely played an important role in the evolution of endothermy.

Influence of ambient temperatures on the heat production of pregnant ewes

1964 ◽  
Vol 15 (6) ◽  
pp. 982 ◽  
Author(s):  
N McCGraham
Keyword(s):  
Critical Temperature ◽  
Heat Production ◽  
Fatty Acid Content ◽  
Plasma Free Fatty Acid ◽  
Metabolizable Energy ◽  
Critical Temperatures ◽  
Blood Constituents ◽  
Ambient Temperatures ◽  
Heat Increment ◽  
Urinary Nitrogen

Two Merino ewes were kept on constant diets throughout pregnancy and, after shearing, were exposed to a series of ambient temperatures between 10 and 35°C on several occasions before lambing and once afterwards. Their heat production and urinary nitrogen output were determined at each temperature, and some blood constituents were also measured. Metabolizable energy intakes were 1300 and 1900 kcal/day. The estimated critical temperatures (minimal heat production) of the sheep ranged from 28 to 35°C, being lower at the higher level of feeding and also during pregnancy. A general relationship between thermoneutral heat production per sq. metre and the critical temperature of shorn sheep was derived; the heat increments of gestation and feeding merely increase thermoneutral heat production and so decrease the critical temperature. The heat increment of gestation was 80 and 90 kcal/24 hr/kg lamb at the high and low feeding levels respectively. Fat oxidation (as indicated by the respiratory quotient) and heat production increased up to twofold at subcritical temperatures. At 10°C there was no heat increment due to pregnancy or feeding; blood glucose was increased by 6–9 mg/100 ml in one sheep, and plasma free fatty acid content was highest at 10° in both sheep (0.9 m-equiv./l.). Heat production also tended to be elevated at the highest temperature. The change was greatest (8%) during pregnancy and at the higher level of feeding. Urinary nitrogen increased at the same time only when the sheep were not pregnant. Improved nitrogen economy during gestation was also apparent at other temperatures.

A note on the critical temperature of sucking rabbits

1989 ◽  
Vol 49 (2) ◽  
pp. 333-334
Author(s):  
E. Sanz ◽  
V. Ortiz ◽  
C. de Blas ◽  
M. J. Fraga
Keyword(s):  
Critical Temperature ◽  
Heat Production ◽  
Similar Rate ◽  
Metabolizable Energy ◽  
Energy Requirements ◽  
Critical Temperatures ◽  
Ambient Temperatures ◽  
Energy Retention ◽  
Metabolizable Energy Intake ◽  
New Zealand Rabbits

Five hundred and fifty sucking New Zealand rabbits of three ages (1, 10 and 20 days) were used to measure metabolizable energy intake and heat production at five ambient temperatures varying between 12 and 36°C according to age. Critical temperatures and rate of heat production below them, decreased with age (32, 28 and 24°C; 20·8, 10·8 and 9·2 kJ/kg0·07 per day and °C at 1, 10 and 20 days of age respectively) as a result of the increase in thermal insulation. Energy retention also decreased below critical temperature at a similar rate to the increase of heat production, because rabbits could not increase their milk intake to meet their higher energy requirements.

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