PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Cold Temperature”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources
PubMed1989

Effects of chlorpromazine on hypothalamic aminergic neurons and stress responses in moderate cold.

Guinea-pigs were treated with chlorpromazine or 0.9% NaCl and exposed to +4 degrees C or +23 degrees C for 2 h. Hypothalamic noradrenaline (NA), dopamine (DA), 5-hydroxytryptamine (5-HT), 3-methoxy-4-hydroxyphenylethylene-glycol (MHPG), homovanillinic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) were determined by high-performance liquid chromatography. Serum and urinary catecholamines, muscle and liver glycogen and blood glucose were also measured. Chlorpromazine caused deep hypothermia at this moderately cold temperature and slight hypothermia at room temperature. Cold increased the activity of noradrenergic and serotonergic neurons, as indicated by the increase in hypothalamic MHPG and 5-HIAA and also the MHPG:NA and 5-HIAA:5-HT ratios. A tendency towards drug-induced inhibition of hypothalamic serotonergic neurons was seen, although this was not significant. A drug-induced inhibition of noradrenergic neurons could not be ruled out. Increased drug-induced turnover of DA was observed in the cold, and a tendency in the same direction was seen at room temperature. Excretion of DA into the urine was induced by chlorpromazine. The hypothermic guinea-pigs had low serum catecholamines, indicating diminished sympathetic activity, but high urinary catechols, a sign of cold stress.

Animals↗
PubMed1994

[Determination of reference temperatures for a cold test in digital plethysmography].

BACKGROUND: The purpose of this study was to determine optimal warm and cold temperatures for performance of a cold test. METHODS: Thirty-six healthy volunteers (22 women and 14 men; mean age 40, 94 years, range: 20-58) were included in the study. Plethysmographic signal amplitudes were evaluated at different temperatures (47, 45, 43, 40, 35, 20, 15, 13, 11 and 9 degrees C) under standardized conditions, using digital strain-gauge plethysmographic (Perivein Janssen). Reproducibility was assessed by repetition in the same subject of six digital plethysmography signal measurements at 45 degrees C performed at different times and days. Clinical tolerance was estimated according to an analogue scale. RESULTS: Maximal warm amplitude was obtained at 45 degrees C and maximal vasoconstriction at 13 degrees C. The thermal test was well tolerated for the temperature range between 11 and 45 degrees C. Reproducibility of the measurements was satisfactory. CONCLUSIONS: 45 degrees C is the non-nociceptive reproducible vasoparalyzing reference temperature, allowing measurement of maximal digital circulatory capacities. 11 degrees C should be adopted as the optimal vasoconstriction temperature for performance of a cold test.

Adult↗
PubMed1989

Ambient temperature and food costs: effects on behavior patterns in rats.

Eating, drinking, wheel running, and nesting were recorded continuously in animals living in cages where they foraged for and consumed food by completing operant bar-press requirements. The ambient temperature was either 24 or 0 degrees C. Two food costs, that of initiating meals and that of pellets within meals, were separately manipulated at each temperature. Compared with room temperature, the cold temperature produced a doubling of food and water intake and a greater than twofold increase in nesting time each day. Running behavior was not altered. Regardless of temperature, the cost of initiating meals influenced the frequency and size of meals but did not affect total food intake or time spent feeding, and this cost had no effect on any other activity. As the cost of pellets within meals increased, the time spent feeding increased and there was a decline in daily food intake. The change in intake was greater at the cold temperature because in the cold the rats did not increase daily feeding time sufficiently to maintain intake as pellet cost increased. Such an increase in feeding time would have required that less time be spent in one of the other activities.

Acclimatization↗
PubMed1976

Metabolic adaptations in brown adipose tissue of the hamster in extreme ambient temperatures.

Cold acclimation caused the following changes in the brown adipose tissue (BAT) of the hamster: the relative weight of the tissue increased, it color darkened, the multilocular structure predominated, and tissue protein content increased while fat content decreased. There was also an increase in the mitochondrial protein content. Heat acclimation had the opposite effects, i.e., the color became lighter, total and mitochondrial protein decreased, fat content increased, and tissue structure was mostly unilocular. Accordingly, cold acclimation was accompanied by increased tissue respiration in the presence of chi-glycerophosphate (chi-GP) and succinate, whereas heat acclimation reduced the respiratory activity of the tissue with these substrates. Isolated BAT mitochondria from cold-acclimated animals increased activities of chi-GP and NADH oxidase, whereas the activities of succinic and cytochrome oxidases and the amount of mitochondrial cytochromes were unchanged. The effects of heat acclimation were more pronounced: there was a decrease in the activities of chi-GP, succinic, NADH, and cytochrome oxidases, as well as in the cytochrome a and a3 content. When respiration of tissue slices on succinate was compared to the maximal potential respiration, as measured with mitochondria disrupted by freezing and thawing, it was found that the relative activity (slices vs. disrupted mitochondria) was highest in cold-acclimated animals and decreased progressively with increasing acclimation temperatures. It is suggested that the differences in the apparent activity of the mitochondria were due to changes in the conformation of the mitochondria as a result of acclimation.

Acclimatization↗