The response of mouse skin to combined hyperthermia and X-rays.

The effects of combined hyperthermia and X-irradiation were studied in the skin of the mouse ear. Ears were heated for 1 hour by immersion in a waterbath at temperatures ranging from 37 degrees C--43 degrees C. These heat treatments had little visible effect alone, but when combined with X-rays, enhanced the radiation response. Enhancement depended on the degree of heating. When heat was given immediately after X-rays, the radiation dose to cause a given skin reaction had to be reduced by about 10 per cent for 37 degrees C and about 40 per cent of 43 degrees C. The timing and sequence of the two treatments were important. Heat after X-rays was less effective than heat before X-rays. When heat followed X-rays, the enhancing effect was lost completely if the interval exceeded 4 hours. When heat preceded X-rays, the effect was lost more slowly, depending on temperature. The implications of this for the treatment of cancer by combined therapy are discussed.     

Heat loss responses in rats acclimated to heat loaded intermittently

The present study examined the heat loss response of heat-acclimated rats to direct body heating with an intraperitoneal heater or to indirect warming by elevating the ambient temperature (Ta). The heat acclimation of the rats was attained through exposure to Ta of 33 or 36 degrees C for 5 h daily during 15 consecutive days. Control rats were kept at Ta of 24 degrees C for the same acclimation period. Heat acclimation lowered the body core temperature at Ta of 24 degrees C, and the core temperature level was lowered as acclimation temperature increased. When heat was applied by direct body heating, the threshold hypothalamic temperature (Thy) for the tail skin vasodilation was also lower in heat-acclimated rats than in the control rats. However, the amount of increase in Thy from the resting level to the threshold was the same in all three groups. When heat was applied by indirect warming, threshold Thy was slightly higher in heat-acclimated than in control rats. The amount of increase in Thy from the resting level to the threshold was significantly greater in heat-acclimated rats. In addition, Ta and the skin temperature at the onset of skin vasodilation were significantly higher in heat-acclimated rats. The results indicate that heat-acclimated rats were less sensitive to the increase in skin temperature in terms of threshold Thy. The gain constant of nonevaporative heat loss response was assessed by plotting total thermal conductance against Thy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Heat resistance level of muscles and muscle models of salamander larvae kept at different temperatures and their thermal selection

The larvae of salamanders isolated from 19 pregnant females were grown to the middle of pre-metamorphosis. The siblings obtained from each single female were divided into two parts; larvae of one group were kept at 21 degrees C (control group), and those of the other--at 27 degrees C (experimental group). In all, 38 groups of experimental animals were employed. In animals kept at 21 degrees C the heat resistance of the organism, muscles and contractile muscle models were determined, whereas in those kept at 27 degrees C only the thermoresistance of muscles and their models only was registered. The time of loss of excitability in response to the electrical stimulus during heating in the Ringer solution at 36 degrees C served a criterion of heat resistance of muscles. The time of loss of contractility with the addition of ATP at 36 degrees C was a criterion of heat resistance of muscle models. The time of the onset of thermal shock at 34 degrees C being a criterion of heat resistance of the organism. It has been found that siblings showing a lower resistance level of muscles and of their models at 21 degrees C, when kept at 27 degrees C, increased their resistance much more as did siblings with the initially higher resistance. During the thermal selection, individuals of such initially less resistant families displayed selective advantages.     

The effects of temperature, diet, and other factors on development, survivorship, and oviposition of Aethina tumida (Coleoptera: Nitidulidae)

Developmental rate and survivorship of small hive beetle, Aethina tumida Murray (Coleoptera: Nitidulidae), life stages were measured across different temperatures (21, 25, 28, 32 and 35 degrees C) and diets, which included natural and artificial pollen, honey, and bee pupae. Temperature affected hatch success, time to hatching, and larval growth. Eggs hatched in 61 h at 21 degrees C but in < 22 h at 35 degrees C. Larvae achieved peak weight in < 8 d at 35 degrees C but needed 17 d at 21 degrees C. Diet had comparatively little effect on larval survivorship or maximum weight, although larvae fed only bee pupae had lower survivorship. Access to soil influenced pupation success. Duration of the life stage spent in the soil, during which pupation occurs, was also affected by temperature: adults emerged after 32.7 d at 21 degrees C but after only 14.8 d at 35 degrees C, albeit with high mortality. Minimum temperature for development was estimated at 13.5 degrees C for eggs, and 10.0 degrees C for larvae and pupae. Temperature influenced adult longevity and oviposition: on a honey and pollen diet average adult lifespan was 92.8 d at 24 degrees C but only 11.6 d at 35 degrees C. Beetles lived longer at 28 degrees C or lower but produced the most eggs per female, regardless of diet, at 32 degrees C. Beetle density influenced fecundity: beetles kept at three pairs per vial laid 6.7 times more eggs per female than those kept as single pairs. Overall, beetles fared best at 28-32 degrees C with mortality of all stages highest at 35 degrees C.     

Thermotolerance and thermosensitization in CHO and R1H cells: a comparative study

In CHO and R1H cells thermotolerance was induced by a pre-incubation at 40 degrees C, by an acute heat shock at 43 degrees C followed by a time interval at 37 degrees C, and during continuous heating at 42 degrees C. Thermotolerance, which was tested at 43 degrees C, primarily causes an increase in D0 of the heat-response curve. The degree of maximum thermotolerance was found to be generally more pronounced in CHO than in R1H cells, but the time interval at 37 degrees C, as well as at 40 degrees C, to reach this maximum level was the same in both cell lines. CHO and R1H cells could be sensitized to 40 degrees C by a pre-treatment at 43 degrees C. When compared for the same survival rate after pre-treatment at 43 degrees C alone the degree of thermosensitization was about the same in both cell lines. In either cell line thermosensitization was found to be suppressed when cells were made thermotolerant by a previous incubation at 40 degrees C for 16 hours.     

The relationship between heating time and temperature for rat tail necrosis with and without occlusion of the blood supply

The relationship between time of heating and temperature has been investigated for necrosis resulting in the loss of distal vertebrae in the rat tail. The study was made in both normal conditions and with the blood supply to the tail occluded. In normal conditions there was a transition in the isoeffect relationship close to 42.5 degrees C. Above this temperature a 1 degree C change was equivalent to a change in heating time by a factor of 1.95 +/- 0.01; below 42.5 degrees C the factor increased to 8.1 +/- 0.3. When the tail blood supply was occluded by a clamp the factor was 1.86 +/- 0.01 at temperatures above 42 degrees C and the tissue was considerably more sensitive to hyperthermia. The factor decreased to 1.3 +/- 0.01 at lower temperatures so that the difference in sensitivity between normal and clamped tissue markedly increased with increasing heating time. The results are interpreted in terms of decreased pH resulting from occlusion of the blood supply which renders the tissue more sensitive. The transition in the isoeffect relationship for normal tails is thought to result from the induction of thermal tolerance and is eliminated when the blood supply is occluded. The result is clearly relevant to the heat treatment of regions of tumours with poor blood supply.     

Metabolic costs of heat solicitation calls in relation to thermal need in embryos of American white pelicans

Chilled embryos of pelicans, Pelecanus erythrorhynchos, begin to vocally solicit parental heat at the pipped-egg stage. Honest signalling models predict that if vocal heat solicitation is a true reflection of need, then solicitation should be costly and costs should increase with the embryo's need for warmth. Using open-flow respirometry, we measured the metabolic costs associated with vocal heat solicitation by exposing embryos to either a decreasing or increasing series of body temperatures, ranging from 25 to 37.8 degrees C. We measured baseline costs (stable temperature, embryo silent) and costs associated with cold-induced calling at each temperature. At natural incubation temperature (37.8 degrees C), call rates and costs associated with calling were negligible, as was thermal need. Metabolic costs relative to baseline costs and costs per call increased with thermal need as body temperature declined. Absolute metabolic costs increased between 37.8 and 35 degrees C, then remained stable down to 25 degrees C. Call rates increased as embryos were chilled within the range of temperatures most frequently experienced in nature (35-37.8 degrees C), then decreased significantly for all lower temperatures, probably owing to reduced overall metabolic rate at lower temperatures (25-37.8 degrees C). The results generally support the honest signalling prediction that vocal heat solicitation is metabolically costly, and that costs increase with need. Copyright 1999 The Association for the Study of Animal Behaviour.     

Effect of temperature on kinetics and differential mobility of empty and loaded nucleoside transporter of human erythrocytes

The transmembrane equilibration of [3H]uridine was measured in human erythrocytes as a function of temperature using rapid kinetic techniques. Arrhenius plots of the maximum velocity of equilibrium exchange were continuous between 5 and 30 degrees C (Ea = 17-20 kcal/mol), but the increase in velocity with increase in temperature leveled off above 30 degrees C. This leveling off did not reflect heat inactivation of the carrier since transport activity was stable for 3 h at 37 degrees C. Transmembrane equilibration of uridine in equilibrium exchange and zero-trans modes at 5, 15, 25, and 35 degrees C conformed to appropriate integrated rate equations derived for the simple transporter. The nucleoside transporter exhibited directional symmetry, but the loaded carrier moved on the average 5 times more rapidly than the empty carrier at 15, 25, and 35 degrees C, but 25-40 times faster at 5 degrees C. This marked shift in differential mobility of loaded and empty carrier between 15 and 5 degrees C was entirely attributable to an impairment of mobility of empty carrier. The Michaelis-Menten constant for equilibrium exchange increased about 3-fold with increase in temperature between 5 and 35 degrees C. The van't Hoff plot of the values was approximately linear and yielded an estimate of the enthalpy of carrier:substrate dissociation of 7.8 kcal/mol.     

Interactive effects of solutes, potassium sorbate and incubation temperature on growth, heat resistance and tolerance to freezing of Zygosaccharomyces rouxii.

The interactive effects of solutes, potassium sorbate and incubation temperature on growth, heat resistance and tolerance to freezing of Zygosaccharomyces rouxii were investigated. Growth rates in media supplemented with glucose, sucrose or NaCl to aw 0.93 were more rapid than in unsupplemented media (aw 0.99). Although growth in unsupplemented medium was lower at 35 degrees C, incubation at 21 degrees C or 35 degrees C had little effect on growth in media supplemented with glucose and sucrose. The addition of 300 micrograms potassium sorbate/ml to media resulted in reduced growth rates, particularly at 35 degrees C. Heat resistance of Z. rouxii was substantially greater in cultures previously incubated at 35 degrees C than in cultures incubated at 21 degrees C in media both with and without 300 micrograms potassium sorbate/ml. Zygosaccharomyces rouxii was tolerant to freezing at -18 degrees C for up to 120 d in all test media supplemented with glucose, sucrose or NaCl. The addition of 300 micrograms potassium sorbate/ml to sucrose-supplemented media resulted in increased resistance to freezing in cultures previously incubated at 21 degrees C. Sensitivity to freezing increased when cultures were incubated at 21 degrees C in media not supplemented with solutes. Glucose and sucrose provided the best protection against inactivation by heating and freezing, regardless of the presence of potassium sorbate in growth media.     

Effect of heat treatment on survival of, and growth from, spores of nonproteolytic Clostridium botulinum at refrigeration temperatures.

Spores of five type B, five type E, and two type F strains of nonproteolytic Clostridium botulinum were inoculated into tubes of an anaerobic meat medium plus lysozyme to give approximately 10(6) spores per tube. Sets of tubes were then subjected to a heat treatment, cooled, and incubated at 6, 8, 10, 12, and 25 degrees C for up to 60 days. Treatments equivalent to heating at 65 degrees C for 364 min, 70 degrees C for 8 min, and 75 degrees C for 27 min had little effect on growth and toxin formation. After a treatment equivalent to heating at 85 degrees C for 23 min, growth occurred at 6 and 8 degrees C within 28 to 40 days. After a treatment equivalent to heating at 80 degrees C for 19 min, growth occurred in some tubes at 6, 8, 10, or 12 degrees C within 28 to 53 days and at 25 degrees C in all tubes within 15 days. Following a treatment equivalent to heating at 95 degrees C for 15 mine, growth was detected in some tubes incubated at 25 degrees C for fewer than 60 days but not in tubes incubated at 6 to 12 degrees C. The results indicate that heat treatment of processed foods equivalent to maintenance at 85 degrees C for 19 min combined with storage below 12 degrees C and a shelf life of not more than 28 days would reduce the risk of growth from spores of nonproteolytic C. botulinum by a factor of 10(6).(ABSTRACT TRUNCATED AT 250 WORDS)     

Radiosensitizing and damaging effect of hyperthermia on different biological systems. Radiosensitizing and damaging effect of hyperthermia on cells of mouse La leukemia

When mouse leukosis cell suspensions were subjected to heating the survival rate of animals decreased exponentially with increasing time of heating. It is shown that the increase of temperature for 1 degree C in the range 40-45 degrees C is equivalent to a decrease in the heating time by a factor of approximately 2. The hyperthermia-induced increase in the radiosensitivity of leukosis cells was dependent upon a medium in which heating was performed.     

The effect of heat shock on the growth and mycelial morphology of Streptomyces chrysomallus]

The effect of various conditions of heat shock (1 hour at 35, 38, 40, 42, 45 and 50 degrees C) on the growth and morphological features of Streptomyces chrysomallus, an organism producing actinomycin, was studied. A definite regularity in the mycelium morphological changes at high temperatures was observed. After the shock at 35 and 38 degrees C the biomass volume and morphological features of the streptomycete did not markedly differ from those in the control. The shock at 40 degrees C induced the growth inhibition with decreasing the biomass volume by 50 per cent and appearance of submerged spores. When the shock conditions were more rigid (42, 45 and 50 degrees C) the mycelium growth lacked. It is of interest that the temperature of 42 degrees C induced abundant formation of the spores. With further increasing of the temperature to 45 and 50 degrees C the spore formation was not so abundant. The changes in the growth and development of the streptomycete are discussed in relation to the molecular mechanism of the cell protection from temperature shock.     

Local thermal sensation and finger vasoconstriction in the locally heated hand

The effects of local heating on finger blood flow (BF) and local thermal sensation (Sensw) were studied. Finger BFs in both hands were measured simultaneously; one hand was immersed in water the temperature (Tw) of which was raised from 35 degrees C to 43 degrees C by steps of 2 degrees C every 10 min, while the other hand was kept at Tw 35 degrees C. Finger BF in the locally heated hand decreased at Tw 37 to 41 degrees C, while finger BF in the control hand did not alter. Sensw in the heated hand showed a dynamic response, initially increasing concomitantly with an increase in Tw, then gradually returning and adapting to a new level of Sensw. The dynamic response of Sensw was not perceived during mental calculation even when Tw was raised to 40 degrees C, and the reduction in finger blood flow was not observed. These results suggest that finger vasoconstriction caused by local heating closely relates to the dynamic response characteristic of local thermal sensation at Tw above core temperature, and that the perception of local thermal sensation in the central nervous system is involved in the mechanism of this vasoconstrictor response.     

Thermal stress and Ca-independent contractile activation in mammalian skeletal muscle fibers at high temperatures.

Temperature dependence of the isometric tension was examined in chemically skinned, glycerinated, rabbit Psoas, muscle fibers immersed in relaxing solution (pH approximately 7.1 at 20 degrees C, pCa approximately 8, ionic strength 200 mM); the average rate of heating/cooling was 0.5-1 degree C/s. The resting tension increased reversibly with temperature (5-42 degrees C); the tension increase was slight in warming to approximately 25 degrees C (a linear thermal contraction, -alpha, of approximately 0.1%/degree C) but became more pronounced above approximately 30 degrees C (similar behavior was seen in intact rat muscle fibers). The extra tension rise at the high temperatures was depressed in acidic pH and in the presence of 10 mM inorganic phosphate; it was absent in rigor fibers in which the tension decreased with heating (a linear thermal expansion, alpha, of approximately 4 x 10(-5)/degree C). Below approximately 20 degrees C, the tension response after a approximately 1% length increase (complete < 0.5 ms) consisted of a fast decay (approximately 150.s-1 at 20 degrees C) and a slow decay (approximately 10.s-1) of tension. The rate of fast decay increased with temperature (Q10 approximately 2.4); at 35-40 degrees C, it was approximately 800.s-1, and it was followed by a delayed tension rise (stretch-activation) at 30-40.s-1. The linear rise of passive tension in warming to approximately 25 degrees C may be due to increase of thermal stress in titin (connectin)-myosin composite filament, whereas the extra tension above approximately 30 degrees C may arise from cycling cross-bridges; based on previous findings from regulated actomyosin in solution (Fuchs, 1975), it is suggested that heating reversibly inactivates the troponin-tropomyosin control mechanism and leads to Ca-independent thin filament activation at high temperatures. Additionally, we propose that the heating-induced increase of endo-sarcomeric stress within titin-myosin composite filament makes the cross-bridge mechanism stretch-sensitive at high temperatures.     

Influence of the sporulation temperature upon the heat resistance of Bacillus subtilis.

The influence of different sporulation temperatures (30, 37, 44 and 52 degrees C) upon heat resistance of Bacillus subtilis was investigated. Heat resistance was greater after higher sporulation temperatures. Relation of heat resistance and temperature of sporulation was not linear over all the range of temperatures tested. Heat resistance increased about tenfold in the range of 30-44 degrees C. Sporulation at 52 degrees C did not show any further increase in heat resistance. This effect was constant over all the range of heating temperatures tested (100-120 degrees C). z value remained constant (z = 9 degrees C). Greater heat resistances at higher temperatures of sporulation were not due to selection of more heat resistant cells by a higher sporulation temperature. Spores obtained from cells incubated at 32 or 52 degrees C always possessed heat resistances that corresponded to the sporulation temperature regardless of the incubation temperature of their vegetative cells.     

Pseudomonas putida NCTC 10936 balances membrane fluidity in response to physical and chemical stress by changing the saturation degree and the trans/cis ratio of fatty acids

This study explored the capability of Pseudomonas putida NCTC 10936 to maintain homeoviscosity after changing the growth temperature, incubating resting cells at different temperatures or at a constant temperature in the presence of 4-chlorophenol (4-CP). After raising the growth temperature from 20 to either 30 or 35 degrees C, the degree of saturation of the organism's fatty acids increased and the ratio of trans to cis unsaturated fatty acids decreased somewhat. In contrast, after the incubation temperature of resting cells was raised (grown at 30 degrees C) from 20 to 30 or 35 degrees C the degree of saturation of the fatty acids remained nearly constant, while the ratio of trans to cis unsaturated fatty acids increased. Incubating resting cells (grown at 30 degrees C) at 20 degrees C in the presence of 4-CP again caused no major changes in the degree of saturation, but cis to trans conversion of unsaturated fatty acids was induced, with a corresponding increase in the trans/cis ratios. Increases in both the saturation degree of the fatty acids and the trans/cis ratio of the unsaturated fatty acids correlated with increases in the fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene intercalated in the bilayers of liposomes prepared from the cells of P. putida NCTC 10936. Electron transport phosphorylation (ETP) could be stabilized by adaptive adjustments in the fluidity of the cytoplasmic membrane mediated by changes in fatty acid composition such as those observed. Whether changes in the degree of saturation or in the trans/cis ratio are more effective can be decided by studying P. putida NCTC 10936.     

Effects of local hyperthermia on the motor function of the rat sciatic nerve

The effect of local heat treatment of the sciatic nerve was assessed using the toe-spreading test, which mainly assesses the motor function of the sciatic nerve. A 5 mm long segment of the nerve was heated at temperatures from 42.0 to 45.0 degrees C in vivo using a brass thermode. Hyperthermia led to a decrease in spreading of the toes. Recovery from functional loss took place in all cases, and this recovery was completed in 4 weeks. A 50 per cent functional loss in 50 per cent of the treated animals was observed after 58, 32 and 12 min of heating at 43.0, 44.0 and 45.0 degrees C respectively.     

Hyperthermia and the immune response in cancer therapy

Summary There is considerable circumstantial evidence that the immune system is involved in the tumour regression and host cure that may follow curative local tumour heating in animals. There is little to indicate that a specific anti-tumour immune response is stimulated following heating or that heat per se is in any way unique in its effect on tumours. Available data suggest that the participation of the immune response involves macrophages and an increase in non-specific cellular and humoral immune competence. Total-body hyperthermia can depress these reactions, probably by direct physical damage to lymphoid tissues, and so predispose to enhanced metastasis. In man, results obtained with bacterial preparations are also consonant with a non-specific boosting effect on host defences via stimulation of the reticuloendothelial system. There is no definitive evidence for stimulation of an effective anti-tumour response in man following tumour heating, and no indication that total-body heating is deleterious to host defence mechanisms.Current data suggest that the more defined host response to tumour heating in animals is an artifact, due to the greater chemically induced antigenicity (immunogenicity) of animal tumours used for research.     

Influence of heat transmission mode on heating rates and on the selection of patches for heating in a mediterranean lizard

Heliothermy (heat gain by radiation) has been given a prominent role in basking lizards. However, thigmothermy (heat gain by conduction) could be relevant for heating in small lizards. To ascertain the importance of the different heat transmission modes to the thermoregulatory processes, we conducted an experimental study where we analyzed the role of heat transmission modes on heating rates and on the selection of sites for heating in the Mediterranean lizard Acanthodactylus erythrurus (Lacertidae). The study was conducted under laboratory conditions, where two situations of different operative temperatures (38 degrees and 50 degrees C) were simulated in a terrarium. In a first experiment, individuals were allowed to heat up during 2 min at both temperatures and under both heat transmission modes. In a second experiment, individuals were allowed to select between patches differing in the main transmission mode, at both temperatures, to heat up. Experiences were conducted with live, nontethered lizards with a starting body temperature of 27 degrees C. Temperature had a significant effect on the heating rate, with heat gain per unit of time being faster at the higher operative temperature (50 degrees C). The effect of the mode of heat transmission on the heating rate was also significant: at 50 degrees C, heating rate was greater when the main heat transmission mode was conduction from the substrate (thigmothermy) than when heating was mainly due to heat gain by radiation (heliothermy); at 38 degrees C, heating rates did not significantly differ between transmission modes. At 38 degrees C, selection of the site for heating was not significantly different from that expected by chance. However, at 50 degrees C, the heating site offering the slowest heating rate (heliothermic patch) was selected. These results show that heating rates vary not only with environmental temperature but also with different predominant heat transmission modes. Lizards are able to identify and exploit this heterogeneity, selecting the source of heat gain (radiation) that minimizes the risk of overheating when temperature is high.     

Influence of single administration of different diets on the energy metabolism at temperatures of 10,20 and 30 degrees C in the golden hamster.

Fed animals have a higher resting metabolic rate in the thermoneutral zone than fasting ones. The metabolic increase is due to the specific dynamic action of food. With a decline of environmental temperature this increase in metabolism either declines or remains unchanged; decisive is whether the heat is used for thermoregulation or not (Mejsnar and Jansky 1971). The objective of our work was to find out to what extent a single intake of a diet with a different ratio of nutrients can influence resting metabolism in the golden hamster and whether this heat can be used for thermoregulation in the cold. Female golden hamsters aged 6-8 weeks kept at a constant temperature of 22 +/-1 degrees C with twelve-hour alternation of light (6 a.m. - 6 p.m.) and darkness ( 6 p.m. - 6 a.m.) were used for the experiments. The oxygen consumption was assessed after a single intake of a standard, high-carbohydrate (76 cal.% starch), high-fat (80 cal.% margarine) and high-protein (82 cal.% casein) diet-for detailed composition see Fábry (1959). The food was given at 6.m. after previous 20 hours of fasting. Animals were then transferred into the respiration chamber and kept there for three hours, including one hour when they were left to settle down; during this period the oxygen consumption was not measured. Oxygen consumption measurement started at 9 a.m. and lasted till 11 a.m. The metabolism of the animals at rest was assessed at temperatures of 10, 20 and 30 degrees C by measuring the oxygen consumption by the interferometric method (Wollschitt et al. 1935). The results are expressed in ml of oxygen per g of body weight per hour. The relationship between the metabolism at rest and environmental temperatures in hamsters given a single dose of standard, high-proetin, high-fat or high-carbohydrate diet is apparent from Table 1. The maximum increase of oxygen consumption after administration of the experimental diets was found at a temperature of 30 degrees C. At an environmental temperature of 20 degrees C the administration of the high-protein and high-fat diet causes roughly the same increase of metabolism. The high-carbohydrate diet increase is only one third of thevalues found, in the remaining two diets at the same temperature and is non-significant. At the environmental temperature of 10 degrees C all the diets used increased the oxygen consumption insignificantly. The changes in metabolism at different environmental temperatures after administration of various diets expressed as percentage of metabolism at 30 degrees C in animals fed the standard diet indicate that the specific dynamic action of the high-protein and high-fats diets is lower at lowered temperatures. We may thus assume that the heat produced as a result of specific dynamic action of the high-protein and high-fat diets is perhaps used for thermoregulation. The role of specific dynamic action of high-carbohydrate diet for thermoregulation is not clear from our experiments. The role of specific dynamic action of food was assessed by several authors...