The oxygen consumption rates of virgin and lactating rats fed ad libitum were measured at temperatures ranging from 1 to 28 degrees C. The oxygen consumption rates of the virgin animals decreased progressively with increasing ambient temperature, but those of the lactating animals decreased slightly between 1 and 8 degrees ...

Angiotensin II (AII, 5 micrograms) injected into the cerebral ventricles produced hypothermia in conscious rats at ambient temperatures (Ta) of 18, 23, and 28 degrees C. At Ta of 18 and 23 degrees C, AII-induced hypothermia was attributed to both enhancement of heat loss and suppression of metabolic rate. At ...

The effects of field stimulation and ionophoretic application of adenosine triphosphate (ATP) and noradrenaline were studied in the rat anococcygeus by means of an intracellular microelectrode. Field stimulation at room temperature produced three types of electrical membrane response: (a) a 'fast' excitatory junction potential (e.j.p.) which had a latency of ...

The present study measured oxygen consumption and core body temperature following central injections of bombesin (1.0 microgram) in food-deprived rats. Oxygen consumption did not differ for bombesin- and control-injected rats while mean core body temperature decreased significantly following bombesin administrations. Present findings suggest separate mechanisms of heat loss for bombesin-induced ...

A new simple but general estimation method for survival time in a hot environment is presented in this study. Even in heat-tolerant rats showing a triphasic heat response, an accurate estimation of survival time (ST) is possible. Rat groups, which included some heat-tolerant individuals, were exposed to 42.5 degrees C, ...

The effect of reduction in temperature of perfusion from 37 to 27 degrees C and 20 degrees C on the ability of the adrenoceptor antagonists indoramin and labetalol to block pressor responses to noradrenaline in the perfused mesenteric vascular bed of the rat was examined. The results suggest that in ...

Laboratory white rats and fossorial mole rats (Spalax ehrenbergi) were subjected to progressive hypoxia by enclosure in a thermoregulated, confined atmosphere. Variable levels of environmental CO2 were obtained by controlling the duration of CO2 absorbance. Rats had preimplanted electroencephalographic (EEG) and electrocardiographic (EKG) electrodes and a rectal temperature probe. Animals ...

The surface temperature of a rat's paw is greatly affected by heat transfer because of its contacts with the body, as well as several environmental conditions. To establish a methodology for determining the surface temperature of the inflamed rat's paw, we devised an individual cage with a pair of rolling ...

The activity of antidromically identified supraoptic neurosecretory neurones was recorded in Sprague-Dawley rats under urethane or sodium pentobarbitone anaesthesia during cooling of the body with a cold pack. Of twelve phasic neurones studied during a complete cooling and rewarming cycle, six displayed an initial increase, followed by a depression in ...

It was shown, by selective levels of decerebration, that a drop in body temperature occurred in a midpontine rat due to impairment in thermoregulatory responses. Lowering the level of decerebration to the lower pons restored a coordinated thermoregulatory response. The response was inadequate to raise the core temperature to normal ...

Rats were chronically implanted with a hypothalamic thermode. After recovery the thermode was heated and the rats were exposed to 4 ambient temperatures (Ta) 20, 30, 35 and 40 degrees C. For each Ta they were subjected to 3 conditions: (1) they could press a bar which provided them with ...

Heat conservation and production were studied in rats at 3 G and at 1 G. A closed-circuit system that includes a Krogh-type spirometer for the continuous measurement of oxygen consumption was used to determine heat production. At the same time, core temperature (Tc) and tail temperature (Tt) were also measured. ...

The energy expenditure of normal and congenitally obese adult female Zucker rats has been measured by continuous indirect calorimetry for periods of 3-10 days at ambient temperatures varied from 30 to 5 degrees C. Rectal temperatures were also recorded. Exposure to cold caused no ill-effects in normal or obese rats. ...

A study was conducted in rats to determine solubility and subsequent metabolism of an inhaled aerosol of curium treated at high temperatures. Young adult Fischer-344 rats received a single inhalation exposure to one of three monodisperse aerosols of 244Cm2O3 (0.70, 1.3, or 2.6 micron activity median aerodynamic diameter) heat-treated at ...

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 ...

Crude synaptosome (P2) fractions prepared from rat striatum and hypothalamus, preloaded with 3H-dopamine (DA) or 3H-norepinephrine (NE), were incubated at 37 degrees C for 5 min. The addition of reserpine at a concentration of 0.1 microM to the striatal synaptosomes substantially depleted 3H-DA to about 45% of control values, but ...

The effective dose-50 (ED-50) for halothane anesthesia was studied in 45 male Mongolian gerbils at age 12 weeks. Close control of circadian variation and animal temperature was maintained. Regression analysis for the percent of animals moving in response to a standard stimulus revealed an ED-50 of 1.32 volumes %, a ...

Female rats which were exposed to supine restraint plus cold for 3 hr and were able to bite a passing nylon brush, developed fewer gastric lesions as compared to control rats which were similarly restrained but did not have access to the aggressive biting response. A second study, wherein rats ...

The effect of hypoglycaemia (blood glucose 1 mmol/l) on the axonal transport of acetylcholinesterase activity and noradrenaline was examined in non-diabetic rats. Rats were made hypoglycaemic over a 6-h period during which acetylcholinesterase and noradrenaline accumulated proximal to a tight ligature applied to the left sciatic nerve. The hypoglycaemic rats ...

A study was made of the effects of pretreatment with fractionated capsaicin on the changes in body temperature (Tb) induced in rats by exposure to cold and to warm environments, and by administration of histamine (40 mg X kg-1) or of pentobarbital (20 mg X kg-1). At the ambient temperature ...

To test the proposal that mammals have parallel neurocontrollers for temperature regulation, Long-Evans hooded male rats were exposed to cold while in a 3-G field. When exposed to cold, these rats consumed 35% less oxygen/min at 3 G than they did when exposed to cold at 1 G. However, rats ...

Restraint hypothermia has often been described, but its cause has never been clarified. We hypothesized that it might be due to a suppression of shivering thermogenesis. Thus, we restrained conscious rats in an ambient temperature of 2 degrees C while measuring rectal (Tre) and tail skin temperatures, metabolic rate (MR), ...

Short-lasting hypothermia during thiobutabarbital general anaesthesia causes no decrease of the absolute ATP level in the blood and liver of rats. The adenylate energy charge in the tissues is relatively high - 0.86 in the liver and 0.85 in the muscles, which might be an evidence of a significant "energy ...

Three male Mongolian gerbils displayed schedule-induced polydipsia on a fixed-time 3-min food reinforcement schedule at 85% body weight (BW). When the gerbils' body weights were gradually increased to ad lib levels, the polydipsia disappeared. When the gerbils were subsequently reduced to 85% BW again, the previous polydipsia levels of water ...

Two experiments were conducted to determine the influence of feather cover and newly-devised insulative jackets on the heat production in Single Comb White Leghorn laying hens at 20 C. An open-circuit calorimeter was used to measure the gaseous exchange of the birds. With ad libitum feeding, birds with clipped back ...

Intracerebroventricular administration of bombesin, a naturally-occurring peptide, produces hypothermia in the rat. To determine whether a pituitary-dependent step is necessary for this effect, the thermoregulatory response was followed in hypophysectomized and intact rats maintained at room temperature. Significant hypothermia was produced in both experimental groups. This study supports an extra-pituitary ...

The metabolic response to a standard burn injury in rats (25% of body surface area) was investigated at environmental temperature 20 degrees C and 30 degrees C. With an intake of 15 g diet (20% w/w protein) per day, burned rats at 20 degrees C were found to be in ...

Rats with hypothalamic thermodes had their hypothalamus cooled or warmed for short sessions. In a first series of experiments, rats could bar-press to obtain fanning with cool air. Cooling the hypothalamus did not suppress or inhibit this behaviour although rectal temperature was markedly increased. In a second series of experiments, ...

p-Chlorophenylalanine (PCPA), a serotonin depletor, was used to investigate thermoregulation of unrestrained unanesthetized rats exposed to warm (approximately 32 degrees C) and cold (approximately 3 degrees C) environments. PCPA (300 mg/kg, ip) was administered approximately 48-96 h prior to the experimental trials. After 60 min of warm exposure, PCPA-treated rats ...

1. Plasma albumin synthesis was measured in rats and sand rats (Psammomys obesus) during heat acclimation (34 degrees C) and following thermal dehydration (37 degrees C) using 3H 1-leucine as a tracer. 2. In rats, heat acclimation resulted in 48% reduction in albumin synthesis. In sand rats synthesis increased by ...

Exposure of pinealectomized rats to high ambient temperature (35 degrees C; PXH) brought about a diminution in pituitary weight and LH content when compared to their sham-operated peers (35 degrees C) or to pinealectomized controls (22 degrees C). Serum corticosterone level of PXH rats was significantly depressed while heat or ...

1. Acclimation of laboratory rats Rattus norvegicus albino to long scotophase 8L:16D and 4L:20D at an ambient temperature (Ta) of 25 degrees C caused an increase in urinary free catecholamine compared to 12L:12D at Ta = 25 degrees C. 2. Transferring the same individuals from 8L:16D to 12L:12D (at Ta ...

1. Exposure of rats to a temperature of 1 degree C resulted in a temporary decline in respiratory quotient to a minimum on the 4th day of exposure, with subsequent recovery. 2. Metabolism stabilized after 4-6 days of cold exposure. 3. Body composition was determined for control rats and rats ...

Clearance and degradation of the glycoprotein, asialofetuin (AF), by the isolated perfused rat liver at supranormal temperatures were investigated. The half-life for disappearance of AF was similar at 37, 41, and 42 degrees C, P greater than 0.05. There was a significant difference between the amount of hydrolysis of AF ...

1. Rats reared from birth in air at 30 degrees C showed a decreased ability to maintain colonic temperature when exposed to 10 degrees C as compared with rats reared at 20 degrees C. This difference was not due to physical factors affecting heat loss, such as surface area or ...

Rats were given D- and/or L-aspartic acids (Asp) in saccharin solution for one week. Body weight gain, daily food and fluid intake, weight of faeces, urine outflow and osmolality, and rectal temperature were compared with those of the pretreatment period. After the rats had been sacrificed the weights of liver, ...

Budipine, a new potential antiparkinsonian drug, did not affect or--in higher doses--inhibited the flexor reflex in spinal rats, having no influence on LSD- or fenfluramine-induced flexor-reflex stimulation. It did not affect the body temperature either of the rat kept at a high ambient temperature or of the rabbit in a ...

Heat-stressed rats thermoregulate behaviorally by spreading saliva onto body surfaces and thus lose body water through evaporative cooling. Prior to exploring the role of dehydration in our rat heatstroke model, we sought to compare the abilities of physical restraint, surgical desalivation, and/or atropine to increase the rate of body heat ...

The nasoturbinates and maxilloturbinates have previously been reported to be completely resorbed in Wistar rats reared at 32-33 degrees C from 3 weeks to 6 months of age. The phenomenon was reinvestigated for the first time in the experiments reported here, with dramatically different results. Rats reared at 33 degrees ...

The role of the thyroid in the mediation of an estrogen-associated change in thermal balance was studied in thyroidectomized and in propylthiouracil-treated ovariectomized rats. Prior to propylthiouracil treatment, estrogen-treated ovariectomized rats and intact female rats had higher rates of heat production and dry heat loss at -5 degrees C than ...

The regulation of ketone-body metabolism and the quantitative importance of ketone bodies as lipid precursors in adult rat brain has been studied in vitro. Utilization of ketone bodies and of pyruvate by homogenates of adult rat brain was measured and the distribution of 14C from [3-14C]ketone bodies among the metabolic ...

The effects of post-training and/or pretesting body cooling on retention of Pavlovian discriminated fear conditioning were examined in preweanling (16-day) and weanling (23-day) rats. Twenty-four retention was assessed in 16- and 23-day-old rats receiving hypothermia after training, after training and prior to testing, or at neither time. Amnesia was present ...

Prostaglandin D2 (PGD2) is the most common prostaglandin type of the rat brain. Recently a neuromodulator role for PGD2 has been suggested. In the present work the central cardiovascular and thermal effects of PGD2 were studied in urethane-anaesthetised rats. When administered at the doses of 0.001-10 micrograms/rat into the lateral ...

The mode of fragmentation of chromatin by micrococcal nuclease has been studied in nuclei from different sources at physiological ionic strength and low temperature. During digestion, the size of chromatin was reduced until an average S value of 95-100 (hen erythrocyte) or 60-65 (rat liver) was attained. The accumulation of ...

Calorigenic effect of glucagon on whole body oxygen consumption and interscapular brown adipose tissue (BAT) was investigated in unanesthetized and unrestrained warm controls (WC), cold-acclimated rats (CA) and heat-acclimated rats (HA). Glucagon produced significant elevation of oxygen consumption, body temperature and BAT temperature in all experimental groups. Such increased calorigenic ...

The chronotropic and inotropic effects of 2.45-GHz continuous wave (CW) microwave radiation were investigated in the isolated spontaneously beating rat atria. Isolated atria were placed in specially designed tubes inserted into a waveguide exposure system. The atria were then irradiated for a period of 30 min, followed by a 30-min ...

Fibrillar cytoplasmic bodies, generally referred to as nucleolus-like bodies (NLBs), have been observed in the embryonic ectodermal cells of early postimplantation rat embryos. The NLBs are not delineated by a membrane, and consist of 5-7 nm filaments. The diameter of the NLBs varies widely, but 0.7-1.2 micrometer is common. Small ...

1. Unanaesthetized, female white laboratory rats were subjected to almost square-wave changes in ambient temperature, from 20 degrees C to 35 degrees C, in a small climatic chamber. 2. Intracerebroventricular injections of serotonin and methysergide were made in shivering, unanaesthetized rats. 3. The integrated electromyogram of m. suprascapularis was recorded ...

1. Both shivering and nonshivering thermogenesis are ways of increasing oxygen consumption in the rat. The participation of nonshivering thermogenesis after cold acclimation is well established, but there is little evidence of the relative importance of each kind of thermogenesis in acclimated and nonacclimated rats. 2. Oxygen consumption and rectal ...

The irritant effect of repeated inhalation exposure to vapors of aqueous formalin (formaldehyde concentration, 15 ppm) in male Charles River CD rats and male C57BL6/F1 mice was determined. The data suggest that rats are relatively insensitive to this irritant while mice are substantially more sensitive, the latter showing a comparable ...