PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Body 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 73 records · Page 4Linked to original sources
PubMed1988

Involvement of GABA in environmental temperature-induced change in body temperature.

Acute exposure of adult male albino rats (110-120 g) to higher environmental temperature (40 +/- 1 degrees C) increased body temperature (BT). This increase of BT was also dependent on the duration of exposure. Treatment with muscimol (1 mg/kg, i.p.), a GABA agonist, produced hypothermia at room temperature (28 +/- 1 degree C) and resistance to increase the body temperature when exposed to higher temperature (40 +/- 1 degree C). Administration of bicuculline (1 mg/kg, i.p.), a GABA antagonist, on the other hand, enhanced BT more than that observed in control (normal) rat exposed to higher temperature (40 +/- 1 degree C), although at room temperature bicuculline treatment did not show any effect on BT. Pretreatment with ethanolamine-O-sulfate (EOS) (2 g/kg, s.c.), a GABA transaminase inhibitor, to rats exposed to higher temperature increased BT as in control (normal) rat. Inhibition of central GAD activity with mercaptopropionic acid (MPA) (70 mg/kg, i.p.) produced resistance to increase BT during its period of action when rats were exposed to higher environmental temperature (28 +/- 1 degree C). These results thus suggest that central inhibitory neuron, GABA, plays a regulatory role in thermoregulation.

3-Mercaptopropionic Acid↗
PubMed2002

Relationship between alertness, performance, and body temperature in humans.

Body temperature has been reported to influence human performance. Performance is reported to be better when body temperature is high/near its circadian peak and worse when body temperature is low/near its circadian minimum. We assessed whether this relationship between performance and body temperature reflects the regulation of both the internal biological timekeeping system and/or the influence of body temperature on performance independent of circadian phase. Fourteen subjects participated in a forced desynchrony protocol allowing assessment of the relationship between body temperature and performance while controlling for circadian phase and hours awake. Most neurobehavioral measures varied as a function of internal biological time and duration of wakefulness. A number of performance measures were better when body temperature was elevated, including working memory, subjective alertness, visual attention, and the slowest 10% of reaction times. These findings demonstrate that an increased body temperature, associated with and independent of internal biological time, is correlated with improved performance and alertness. These results support the hypothesis that body temperature modulates neurobehavioral function in humans.

Adult↗
PubMed2001

Effects of caffeine and high ambient temperature on haemodynamic and body temperature responses to dynamic exercise.

Caffeine can enhance mean arterial blood pressure (MAP) and attenuate forearm blood flow (FBF) and forearm vascular conductance (FVC) during exercise in thermal neutral conditions without altering body temperature. During exercise at higher ambient temperatures, where a greater transfer of heat from the body core to skin would be expected, caffeine-induced attenuation of FBF (i.e. cutaneous blood flow) could attenuate heat dissipation and increase body temperature (T(re)). We hypothesized that during exercise at an ambient temperature of 38 degrees C, caffeine increases MAP, and attenuates FBF and FVC such that T(re) is increased. Eleven caffeine-naive, active men, were studied at rest and during exercise after ingestion of a placebo or 6 mg kg(-1) of caffeine. MAP, heart rate (HR), FBF, FVC, T(re) skin temperature (T(sk)) and venous lactate concentrations (lactate) were assessed sequentially during rest at room temperature, after 45 min of exposure to an ambient temperature of 38 degrees C, and during 35 min of submaximal cycling. Heat exposure caused increases in MAP, FBF, FVC and T(sk) that were not altered by caffeine. HR, T(re), and lactate were unaffected. During exercise, only MAP (95 +/- 2 vs. 102 +/- 2 mmHg), HR (155 +/- 10 vs. 165 +/- 10 beats min(-1)), and lactate (2.0 +/- 0.4 vs. 2.3 +/- 0.4 mmol l(-1)) were increased by caffeine. These data indicate that increases in cutaneous blood flow during exercise in the heat are not reduced by caffeine. This may be because of activation of thermal reflexes that cause cutaneous vasodilation capable of offsetting caffeine-induced reductions in blood flow. Caffeine-induced increases in lactate, MAP and HR during exercise suggest that this drug and high ambient temperatures increase production of muscle metabolites that cause reflex cardiovascular responses.

Adult↗
PubMed2003

Suitability of temperature-sensitive transponders to measure body temperature during animal experiments required for regulatory tests.

Body temperature is a clinical parameter in vaccine quality control to detect systemic side-effects or to monitor progression of infectious diseases. Moreover, changes in body temperature are used as clinical parameters to define humane endpoints in animal experiments. However, measuring body temperature via the rectal route can be troublesome and distressing to the animal. Non-invasive measurement methods were developed in recent years. The aim of this investigation was to study and to compare rectally measured body temperature with data obtained with implanted temperature-sensitive transponders (TST) in mice, guinea pigs, rabbits and pigs under the controlled conditions of regulatory testing.

Animals↗
PubMed1986

Prediction of ovulation with basal body temperature.

Basal body temperature (BBT) is used extensively to monitor ovulation in the treatment of infertility. There are well-defined methods of interpreting the BBT graph retrospectively that identify a presumptive day of ovulation. The prediction of ovulation through utilization of the BBT graph (strictly concurrent interpretation) is adversely influenced by temperature fluctuation and cycle length variability. The BBT graph can be very useful when its interpretation is well defined and its limitations understood.

Body Temperature↗
PubMed1995

Higher environmental temperature-induced increase of body temperature: involvement of central opioidergic-GABAergic interaction.

Exposure (2 h) of male albino rats to higher environmental temperature (HET, 40 degrees C) significantly increased the body temperature (BT). Administration of bicuculline (1 mg/kg, i.p.), physostigmine (0.2 mg/kg, i.p.), or their combination significantly raised the BT of normal rats (kept at 28 degrees C) or of HET-exposed rats. Atropine (5 mg/kg, i.p.) abolished the hyperthermic effect of bicuculline in normal and HET-exposed rats. The BT of normal and HET-exposed rat was increased with morphine (1 mg/kg, i.p.) and was reduced with naloxone (1 mg/kg, i.p.). Bicuculline or physostigmine-induced rise in BT of HET-exposed rats was potentiated following cotreatment of physostigmine with morphine. Atropine-induced hypothermia was abolished due to the cotreatment of atropine with morphine with physostigmine but was attenuated with atropine. In normal rats (kept at 28 degrees C), only atropine attenuated (morphine + bicuculline)-induced hyperthermia. L-Dopa + carbidopa or haloperidol did not significantly affect the BT of rats under similar conditions. These results suggest that short-term (2 h) exposure to HET activates the opioidergic neuron, which activates cholinergic activity through the inhibition of GABAergic system and, thus, enhances the BT.

Animals↗
PubMed1986

Factors affecting perioperative body temperature.

Factors affecting body temperature in the perioperative period were investigated in two groups of surgical patients (cholecystectomy and repair of fractured femur). Core, toe skin and thigh skin temperatures were assessed pre and postoperatively for all subjects. A control group showed a significant fall in toe skin temperature only during exposure to theatre conditions, whereas all of the surgical patients underwent falls in core temperature. The fractured femur patients sustained significantly greater reductions in core temperature than the cholecystectomy patients. Age and ambient theatre temperature were found to be the most influential factors affecting this fall in core temperature. Body composition had less of an influence than these two variables, but it was found that the patients with the greatest body fat contents had the smallest reductions in core temperature. Seven of the 31 patients returned to the ward with core temperatures below 35 degrees C, and only one of these seven received assistance in rewarming. Four of the 31 patients developed significantly higher core temperatures than the remaining 27 during the immediate postoperative period, and these four subsequently developed respiratory tract infections. Standard monitoring of temperature on the wards during the immediate postoperative period failed to identify postoperative hypothermia or pyrexia in the majority of cases.

Adult↗
PubMed1984

Effect of dietary restriction and stress on body temperature in rats.

Body temperature was measured in 6- and 24-month-old Sprague-Dawley rats that were either kept on a restricted diet or fed ad libitum. The circadian variation of body temperature was similar in 24-month-old restrained, restricted, and control rats. Feeding of rats increased their body temperature. The process of temperature measurement also increased body temperature of rats. This stress-induced increase of temperature was larger in younger than in older rats and was diminished in ad-libitum-fed rats by 24-hr fasting. The stress-induced increase in rats on restricted diet that were fasted 24 hrs before the experiment was similar to that observed in 24-hr-fasted ad-libitum-fed rats. These results show that appropriate controls should be used when the effect of chronic food restriction is being investigated to distinguish between the effect of short-term fasting and long-term food restriction. These results also indicate that the increase of life span induced by dietary restriction in rats is not associated with decreased body temperature as was observed in some strains of mice.

Age Factors↗
PubMed1986

The influence of ambient temperature on metabolism and body temperature of newborn and growing reindeer calves (Rangifer tarandus tarandus L.).

Thermoregulatory capacities of 51 reindeer calves (Rangifer tarandus tarandus L.) aged 1-35 days were studied at -26.5 to +35.0 degrees C ambient temperatures at Kaamanen reindeer research station, Finland (69 degrees 10' N) during calving periods in May 1981 and May-July 1982. The newborn calves aged 1-4 days maintained a high body temperature (Tre) (mean +40.2 degrees C) even at the lowest experimental temperature of -22.5 degrees C by increasing their metabolic rate five-fold above the level at +11.0 degrees C. Heat production of the new-born calves was largely based on the metabolism of brown adipose tissue, stimulated by cold-induced discharge of the sympathetic nervous transmitter, noradrenaline (NA). Sensitivity of the calves to exogenous NA disappeared during the first 3-4 weeks of life. Thermal conductance of the calves was low at low ambient temperatures, but rose strongly as Ta increased above +10 degrees C. The extensive peripheral cooling, especially in the feet, was demonstrated in the calves aged 1-10 days. The lowest foot temperature (+10.5 degrees C) was measured in a 4-day-old calf at -14.5 degrees C. Slight shivering thermogenesis was recorded in the calves aged 1-4 days and occasionally in the older calves at low values of Ta. Shivering appears to be a reserve mechanism against severe cold. At about +20 degrees C and above the calves increased their Tre (approximately 1 degree C), oxygen consumption and heart rate. In the newborn calves oxygen consumption rose four- to five-fold and in 1-month-old calves about two-fold. Fast growing calves (maximum 400 g/day) appear to be more stressed by heat than by cold exposure.

Aging↗
PubMed2001

Individual variation in the relation between body temperature and energy expenditure in response to elevated ambient temperature.

The question we address here is whether a mild increase in environmental temperature affects body temperature and energy expenditure, focusing on the individual variation in the relation between energy expenditure and body temperature. We studied eight normal weight healthy females, 48 h at an ambient temperature of 22 degrees C, and 48 h at 27 degrees C. Energy expenditure (EE) was measured in a respiration chamber. Subjects' skin temperature was measured continuously from 8:00 a.m. until 12:00 p.m.: forehead, infraclavicular zone, thigh, hand, and foot. Core temperature was determined tympanically. Body composition was determined by under water weighing. Exposure to 27 degrees C caused a significant increase in body temperature (both skin and core), a decrease in temperature gradients, and a decrease in energy expenditure. At 27 degrees C 24 h EE, adjusted for body composition, was significantly related to body tympanic temperature. The decrease in 24 h EE, at 27 degrees C ambient temperature, was significantly, negatively related to the increase in T(tym), indicating individual responses in adaptation to elevated ambient temperature. Changes in temperature gradient (comparing 27 degrees C with 22 degrees C) were negatively related to changes in EE. This shows that individuals differ in their response to an increase in environmental temperature regarding the relative contribution of insulative or metabolic adjustments.

Acclimatization↗
PubMed1976

Effect of rapid temperature change on mean body temperature and gill ventilation in carp.

Carp were transferred from 25 degrees C water to a calorimeter at 15 degrees C or from 15 degrees C water to a calorimeter at 25 degrees C. During cooling, dorsal muscle temperature (Tdm) and mean body temperature (Tb) were continuously monitored. During the first minutes Tb changed rapidly, while Tdm changed only slightly. In a 0.468-dg fish, Tdm decreased to two-thirds of the final value in 8.05 min, while Tb attained this value in 3.6 min. Tdm changed faster during heating than during cooling. Carp were also placed in a device where gill ventilation (VG) could be continuously monitored while rapid shifts in the temperature of the inspired water (TPINSP) AND/OR BODY SURFACE (Tbs) were effected. Changing Tinsp and Tbs both effected rate-sensitive changes in VG, although Tinsp was more effective. Decreases in Tinsp or Tbs produced decreases in VG; increases in Tinsp or Tbs had an opposite effect. The fish respiratory system is sensitive to the rate of change of external temperature. This sensitivity provides evidence for the existence of peripheral thermal input to the systems regulating respiration in teleost fish.

Adaptation, Physiological↗