AFFERENT DISCHARGE PRODUCED BY MUSCLE COOLING IN MICE MAINTAINED AT NORMAL AND LOW ENVIRONMENTAL TEMPERATURES

1967 ◽  
Vol 45 (2) ◽  
pp. 319-327 ◽  
Author(s):  
M. Banet ◽  
J. J. Séguin
Keyword(s):  
Constant Temperature ◽  
Cold Exposure ◽  
Afferent Activity ◽  
Muscle Receptors ◽  
Muscle Afferent ◽  
Muscle Cooling ◽  
Afferent Discharge ◽  
Afferent Response ◽  
Environmental Temperatures

Muscle receptors in the mouse were shown to discharge in response to cooling of the muscle. Afferent activity was recorded in vitro from the whole nerve of the soleus muscle of 20 male white mice. These animals were maintained at a constant temperature of 22 °C for at least 15 days. In muscles cooled from 37 °C, receptors first showed activity at 32.9 ± 0.89 °C. With further cooling, there was an increase in the number of receptors firing and in the frequency of their discharge. The temperature at which maximum afferent response to cooling (TMA) occurred was 26.6 ± 0.83 °C. Similar experiments were carried out on 61 mice which had been exposed to a constant temperature of 6 °C for periods ranging from 6 hours to 32 days. Sensitivity of the receptors to cooling was significantly decreased following 24 hours' cold exposure (TMA 22.5 ± 1.02 °C) and was lowest after 12 hours' exposure. In animals exposed to cold for 3 days, sensitivity returned to a norma! level (TMA 25.4 ± 1.02 °C), but there was again a decrease in the sensitivity of the receptors to cooling in mice exposed for 5 to 6 days (TMA 22.1 ± 1.13 °C) and in those exposed for 8 to 10 days (TMA 22.4 ± 0.94 °C). Following exposure for 14 to 20 and 30 to 32 days, the sensitivity of the receptors returned to normal levels (TMA 26.3 ± 1.48 °C and 24.6 ± 2.04 °C respectively). At present the mechanisms underlying these changes in sensitivity of muscle receptors to cooling are not known.

In vivo and in vitro lipogenesis and aspects of metabolism in ovines: Effect of environmental temperature and dietary lipid supplementation

2000 ◽  
Vol 80 (1) ◽  
pp. 59-67 ◽  
Author(s):  
J. A. Moibi ◽  
R. J. Christopherson ◽  
E. K. Okine
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Cold Exposure ◽  
Average Daily Gain ◽  
Acid Synthesis ◽  
Dietary Lipid ◽  
Acetate Incorporation ◽  
Lipid Supplementation

Twenty-four wether lambs were randomly allocated to six treatments to investigate the effect of temperature and dietary lipid supplements on fatty acid synthesis and metabolic activity in sheep. The treatments consisted of four groups exposed to either cold (0 °C) or warm temperature (+23 °C) and given ad libitum access to either a control barley-based diet or with lipid supplementation. Two other groups were placed on the dietary regimen at 0 °C, but pair-fed to intake of animals in the +23 °C environment. At 5 wk, fatty acid synthesis was measured by [1-14C]acetate incorporation into tissue lipids. Cold exposure and dietary lipid supplementation had no effect (P > 0.05) on in vivo fatty acid synthesis rates in either longissimus dorsi or the liver. In both subcutaneous and mesenteric adipose tissue depots, the rate of acetate incorporation into tissue lipid was not significantly affected by cold exposure. In the perirenal fat depot, cold exposure increased (P < 0.05) the rate of fatty acid synthesis, while lipid supplementation decreased (P < 0.05) the rate in all tissue adipose depots. In vitro, mesenteric and perirenal adipose tissues from cold pair-fed animals had higher (P < 0.05) rates of fatty acid synthesis compared to tissues from animals in the warm environment. However, there was no effect of dietary lipid supplementation in these two fat depots. Metabolic heat production, and energy and nitrogen excretion by animals were increased (P < 0.05) by cold exposure while lipid supplementation had the opposite effect (P < 0.05). The relationship between average daily gain and feed intake was linear at both warm and cold environments, but with higher (P < 0.05) average daily gain at all levels of intake in the cold compared to the warm environment. Results indicate that both environment and diet regulate metabolic activity in sheep. However, there were differences in lipogenic response by tissues to the treatments. Key words: Environmental temperature, dietary lipid, fatty acid synthesis, metabolic rate, sheep

THE RELATION OF DIETARY PROTEIN LEVEL TO LIVER ENZYME ACTIVITIES IN COLD-EXPOSED RATS

1963 ◽  
Vol 41 (1) ◽  
pp. 1871-1877
Author(s):  
John R. Beaton
Keyword(s):  
Cold Exposure ◽  
Dietary Protein ◽  
Protein Level ◽  
Liver Enzymes ◽  
Albino Rats ◽  
Protein Levels ◽  
Dietary Protein Level ◽  
Phosphate Activated Glutaminase ◽  
Relationship Of ◽  
Environmental Temperatures

Male, albino rats were fed diets containing 5%, 20%, and 40% casein by weight for 7 days at environmental temperatures of 22 °C and 2–3 °C. In one experiment, food was provided ad libitum; in a second experiment, all groups were provided with equal amounts of food. At 22 °C, the activities in liver of alanine-glutamic transaminase, phosphate-activated glutaminase, and arginase increased with increasing dietary protein level. At 2–3 °C, activities of the last two enzymes increased with increasing dietary protein level from 5% to 20% but not from 20% to 40% whereas transaminase activities increased throughout the dietary protein range 5% to 40%. No relationship of glucose-6-phosphatase activity to dietary protein level was evident at either environmental temperature. Cold exposure per se increased the activities of alanine-glutamic transaminase and glucose-6-phosphatase in all dietary protein groups but increased the activities of arginase and phosphate-activated glutaminase only in rats fed the 5% and 20% protein diets. It is postulated that increased activities of these liver enzymes during cold exposure result from augmented catabolism of substrates to meet increased energy requirements. As previously observed with respect to other metabolic alterations, it is apparent that cold exposure modifies the response of liver enzymes to changing dietary protein levels.

Ouabain-sensitive liver and diaphragm respiration in cold-acclimated hamster

1977 ◽  
Vol 42 (2) ◽  
pp. 150-153 ◽  
Author(s):  
B. A. Horwitz ◽  
M. Eaton
Keyword(s):  
Transport System ◽  
Cold Exposure ◽  
Driving Force ◽  
Energy Demands ◽  
Before And After ◽  
Ouabain Inhibition ◽  
K Transport

The in vitro respiratory rates of liver and diaphragm from hamsters were compared before and after prolonged cold exposure (5 degrees C, 3–4 wk). In the presence or absence of glucose, respiratory rates were elevated in both tissues from the cold-acclimated hamsters, and these cold-induced increases were significantly reduced by ouabain. This ouabain inhibition is consistent with the hypothesis that cold exposure of these rodents stimulates the energy demands of the Na+/K+ transport system in liver and diaphragm, with these demands providing a driving force, at least in part, for respiration and accompanying cellular thermogenesis.

Effect of Extreme Cold Exposure on Adrenocortical Function in the Unanesthetized Dog

1956 ◽  
Vol 185 (2) ◽  
pp. 239-242 ◽  
Author(s):  
Richard H. Egdahl ◽  
John B. Richards
Keyword(s):  
Cold Exposure ◽  
Venous Blood ◽  
Adrenocortical Function ◽  
Subsequent Increase ◽  
Adrenal Steroid ◽  
Temperature Ranges ◽  
Exposure Levels ◽  
Healthy Dogs ◽  
The Right ◽  
Environmental Temperatures

Unanesthetized dogs with polyethylene cannulas in the right lumboadrenal vein were subjected to environmental temperatures of –46 to –50°C for 2–28 hours and –75 to –79°C for 4–5 hours. Adrenal venous blood samples were collected prior to, and during the periods of cold exposure, and analyzed for 17-hydroxycorticosteroids. In both temperature ranges, a marked increase in adrenal steroid output occurred soon after the onset of exposure in the 10 dogs studied. In 9 of the 10 animals, this response persisted for 1–3 hours after which adrenal steroid secretion returned to control, pre-exposure levels, despite continued cold exposure. The intravenous administration of 40 iu of ACTH produced a subsequent increase in adrenal 17-hydroxycorticosteroid output. Healthy dogs exposed to temperatures of –47°C for 28 hours and –79°C for 5 hours did not become hypothermic.

Utilization of acetate-1-C14 by hepatic tissue from cold-exposed and hibernating hamsters

1961 ◽  
Vol 200 (5) ◽  
pp. 1043-1046 ◽  
Author(s):  
Arliss Denyes ◽  
Joan D. Carter
Keyword(s):  
Cold Exposure ◽  
Hepatic Tissue ◽  
Hepatic Lipogenesis ◽  
Control Value

When the hamster is exposed to cold (6 ± 1 C), there is a profound block in hepatic lipogenesis from C14-acetate within 48 hr. By 8 weeks of cold exposure this block has been repaired to 74% of the control value. During hibernation, which generally occurs after the 8th week, a block in lipogenesis is again present. By 6 hr of arousal, the degree of lipogenesis has been either slightly repaired or has returned almost to the 8-week level. Accompanying this block in lipogenesis is an increase in the production of C14O2 from C14-acetate in animals exposed to cold. In vitro addition of .02 m glucose did not stimulate lipogenesis in hepatic tissue of cold-exposed hamsters, except for a few of those animals aroused from hibernation for 6 hr. Addition of .02 m succinate in vitro did not increase lipogenesis or C14O2 production from C14-acetate. Fructose repaired the hepatic lipogenesis in all groups of cold-exposed hamsters. It was concluded that the cold-exposed and hibernating hamster has biochemical lesions involving the glucokinase reaction and some other step in the glycolytic pathways of the liver.

Acetate-1-C14 metabolism of white fat from hamsters in cold exposure and hibernation

1963 ◽  
Vol 205 (5) ◽  
pp. 905-908 ◽  
Author(s):  
Joan Baumber ◽  
Arliss Denyes
Keyword(s):  
Cold Exposure ◽  
Room Temperature ◽  
Fat Pad ◽  
Golden Hamsters ◽  
Epididymal Fat ◽  
Cold Room ◽  
White Fat

Incorporation of C14 from acetate-1-C14 into lipid and CO2 by epididymal fat from golden hamsters kept at room temperature, acclimated to 5 ± 1 C, in hibernation and arousing from hibernation, was measured in vitro at 37 C. Summer and winter series were compared. The C14O2 production by tissue from control and acclimated animals was similar but the C14O2 production of tissue from hibernating and arousing hamsters was significantly greater than that from acclimated animals. There was a large increase in the lipid-C14 of tissue from cold-acclimated animals and this increase persisted into hibernation but was slightly depressed in tissue from arousing animals. Many acclimated and all hibernating hamsters had involuted testes and a greater incorporation of C14 into lipid than those with noninvoluted testes. A greater percentage of hamsters hibernated in the cold room during the winter and at this time the incorporation of C14 into lipid by the fat pad was greater than in the summer.

ROLE OF NA+, K+-ATPase IN MUSCULAR ENERGY EXPENDITURE OF WARM- AND COLD-EXPOSED SHEEP

1982 ◽  
Vol 62 (1) ◽  
pp. 123-132 ◽  
Author(s):  
V. A. GREGG ◽  
L. P. MILLIGAN
Keyword(s):  
Skeletal Muscle ◽  
Energy Expenditure ◽  
Cold Exposure ◽  
Whole Body ◽  
Random Group ◽  
Key Words Skeletal Muscle ◽  
Maximum Inhibition ◽  
Functional Membrane

The role of Na+, K+-ATPase in the energy expenditure of sheep skeletal muscle and the influence of exposure to cold on this role were studied. An in vitro preparation of muscle was developed that achieved O2 availability and a functional membrane potential. A 10−6 M concentration of ouabain yielded a maximum inhibition of respiration of 38.9 ± 1.8% using muscle preparations from a random group of sheep. Whole body and muscle O2 consumptions and ouabain-sensitive muscle respiration were measured for warm- and cold-exposed sheep fed at maintenance or 1150 g of alfalfa pellets per day. Cold exposure increased whole body and muscle O2 consumption. Inhibition of respiration by ouabain was 37.6 ± 1.2% and 41.0 ± 3.6% for warm- and cold-exposed sheep fed at maintenance, and 28.5 ± 4.0% and 45.0 ± 4.0% for warm- and cold-exposed sheep fed 1150 g of alfalfa pellets per day. The increase in the ouabain-sensitive component of respiration accounted for 48–79% of the increased O2 consumption of muscle from cold-exposed sheep. It was concluded that the Na+, K+-ATPase of sheep muscle is a major means of energy expenditure and has an important role in the increased thermogenesis resulting from cold exposure. Key words: Skeletal muscle, Energy expenditure, muscle respiration, cold thermogenesis, sodium-potassium transport

In vitro localization of thermosensitive neurons in the rat diencephalon

1989 ◽  
Vol 257 (1) ◽  
pp. R57-R64 ◽  
Author(s):  
J. B. Dean ◽  
J. A. Boulant
Keyword(s):  
Preoptic Area ◽  
Cell Activity ◽  
Wide Distribution ◽  
Thermal Stimulation ◽  
Single Unit Activity ◽  
Tissue Slices ◽  
Single Cell Activity ◽  
Cold Sensitive ◽  
Environmental Temperatures

Many thermosensitive neurons in the preoptic area-anterior hypothalamus (POAH) are believed to function in thermoregulation. Although many other diencephalic regions are implicated in thermoregulation, measurements of single-cell activity during localized thermal stimulation in these regions are lacking. Utilizing horizontal tissue slices, we have recorded single-unit activity throughout the rat diencephalon in response to localized thermal stimulation. Thermosensitive cells were identified in 18 nuclei. The proportions of each subpopulation inside vs. outside the POAH were similar: POAH (n = 83 cells); warm = 31%, cold = 4%, warm-cold = 1%, and temperature insensitive = 64%, outside POAH (n = 198 cells; warm = 39%, cold = 6%, warm-cold = 4%, and temperature insensitive = 51%. However, nuclei located rostral and lateral to POAH contained a large percentage of warm-sensitive cells (49-63%). Caudal nuclei contained approximately half of the cold-sensitive cells studied. This wide distribution of thermo-sensitive cells suggests that many diencephalic areas, besides the POAH, are capable of thermoreception and thermointegration. Moreover, many of these thermosensitive cells may function in other systems (e.g., reproduction, feeding, and water balance) which central and environmental temperatures are known to influence.

Sign in / Sign up

Export Citation Format

Share Document