Temperature regulation during treadmill exercise in the rat

1984 ◽  
Vol 57 (6) ◽  
pp. 1872-1877 ◽  
Author(s):  
F. G. Shellock ◽  
S. A. Rubin
Keyword(s):  
Treadmill Exercise ◽  
Single Stage ◽  
Sprague Dawley ◽  
Work Intensity ◽  
Deep Body Temperature ◽  
Ambient Temperatures ◽  
Sprague Dawley Rats ◽  
Cool Environment ◽  
Colonic Temperature ◽  
Stage 1

The response of colonic and tail-skin temperatures to treadmill exercise was assessed in female Sprague-Dawley rats using incremental and single-stage exercise protocols to investigate the relationship between deep body temperature and work rate. O2 uptake (VO2) was measured by flow-through technique to evaluate the exercise intensity. Experiments were performed in ambient temperatures below (22-25 degrees C) and above (33-35 degrees C) the thermoneutral zone of the rat. During graded incremental exercise there was a linear relationship between colonic temperature (Tco) and VO2 in both the cooler and warmer ambient temperatures. However, Tco and tail-skin temperature (Tsk) at comparable work rates in the cooler and warmer environments were 40.22 +/- 0.59, 34.84 +/- 1.10 degrees C and 42.04 +/- 0.57, 38.39 +/- 1.54 degrees C, indicating that the rise in Tco was unrelated to the severity of exercise. During single-stage exercise the rats were able to achieve thermal equilibrium but only at low work rates and in the cool environment (22-25 degrees C). There were no significant differences in Tco at the first three levels of single-stage exercise (stage 1, 39.63 +/- 0.34 degrees C; stage 2, 39.67 +/- 0.49 degrees C; stage 3, 39.75 +/- 0.50 degrees C) despite significant differences in VO2 (stage 1, 4.3 +/- 0.7 ml X min-1 X 100 g-1; stage 2, 5.3 +/- 0.6 ml X min X 100 g-1; stage 3, 7.6 +/- 1.2 ml X min-1 X 100 g-1). This demonstrates that there was no relationship between the level of Tco maintained during exercise and the work intensity.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of repeated heat exposure on hypothalamic sensitivity to norepinephrine

1980 ◽  
Vol 49 (6) ◽  
pp. 942-945 ◽  
Author(s):  
J. V. Christman ◽  
C. V. Gisolfi
Keyword(s):  
Treadmill Exercise ◽  
Heat Exposure ◽  
Induced Hypothermia ◽  
Guide Tube ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Before And After ◽  
Predetermined Level ◽  
Time Required ◽  
Colonic Temperature

Bilateral stainless steel guide tubes were stereotaxically implanted above the anterior hypothalamus (AH) of 12 male Sprague-Dawley rats (300-360 g). Beginning 3 days postsurgery, norepinephrine (NE) was injected into the AH each day at increasing depths below the guide tube until colonic temperature fell at least 0.8 degrees C. Subsequently, the effects of treadmill exercise at 21.5 m/min for 3 wk at 22 degrees C (n = 6) or 35 degrees C (n = 6) on the magnitude of the NE-induced hypothermia were investigated. Training duration ranged from 12 to 50 min/day, depending on the time required for colonic temperature of the heated rats to rise to a predetermined level: 40.4 degrees C on day 1, increasing 0.1 degree C/day to 41.5 degrees C on day 12 and thereafter. Before and after training, bilateral injections of NE (10 micrograms) at 22 degrees C at rest and just before exercise (21.5 m/min) caused the following mean +/- SE reductions in colonic temperature (degree C). (Formula: See Text). These reductions in colonic temperature were associated with sharp elevations in tail-skin temperature, but there were no significant differences in the response between the two groups. We conclude that repeated heat exposure increased the sensitivity of the AH to exogenous NE.

Heat tolerance of the resting and exercising rat

1968 ◽  
Vol 46 (2) ◽  
pp. 189-194 ◽  
Author(s):  
Sumner M. Robinson ◽  
William F. Blatt ◽  
Carl Teplitz
Keyword(s):  
Heat Load ◽  
Treadmill Exercise ◽  
Heat Exposure ◽  
Progressive Increase ◽  
Sprague Dawley ◽  
Survival Times ◽  
Cardiac Rate ◽  
Ambient Temperatures ◽  
Sprague Dawley Rats ◽  
The Times

Exercising and non-exercising Sprague–Dawley rats were exposed to ambient temperatures between 35 °C and 60 °C, in 5 °C increments. Tympanic and (or) intraperitoneal temperatures were used as indices of body temperature. Mean survival times were 156 min (45 °C) to 21.8 min (60 °C) for the non-exercising rats and 94.8 min (40 °C) to 15.1 min (60 °C) for the exercising groups. It would appear that the treadmill exercise (32 ft/min for alternate 5-min periods throughout the heat exposure) approximated a 5 °C ambient heat load in that the survival times of non-exercising rats were equivalent to the times of exercising rats exposed at a 5 °C lower ambient temperature. Tympanic temperatures recorded at death showed a progressive increase, from 43.8 °C at 40 °C ambient (exercising) to 47.1 °C and 46.9 °C for non-exercising and exercising rats at 60 °C. Circulatory collapse following marked increases in cardiac rate and blood pressure was documented for non-exercising rats at 45 °C ambient.

scholarly journals Differential expression of stress proteins in rat myocardium after free wheel or treadmill run training

1999 ◽  
Vol 86 (5) ◽  
pp. 1696-1701 ◽  
Author(s):  
Earl G. Noble ◽  
Albert Moraska ◽  
Robert S. Mazzeo ◽  
David A. Roth ◽  
M. Charlotte Olsson ◽  
...  
Keyword(s):  
Exercise Training ◽  
Stress Proteins ◽  
Citrate Synthase ◽  
Treadmill Exercise ◽  
Stress Protein ◽  
Critical Factor ◽  
Voluntary Exercise ◽  
Similar Response ◽  
Sprague Dawley ◽  
Sprague Dawley Rats

High-intensity treadmill exercise increases the expression of a cardioprotective, inducible 72-kDa stress protein (SP72) in cardiac muscle. This investigation examined whether voluntary free wheel exercise training would be sufficient to confer a similar response. Male Sprague-Dawley rats were randomly assigned to either treadmill (TM-Tr) or free wheel (FW-Tr) training groups. By the end of the 8-wk training period, TM-Tr animals ran 1 h/day, 5 days/wk up a 10% grade, covering a distance of 8,282 m/wk. FW-Tr rats ran, on average, 5,300 m/wk, with one-third of the animals covering distances similar to those for the TM-Tr group. At the time of death, hearts of trained and caged sedentary control (Sed) animals were divided into left (LV) and right (RV) ventricles. Citrate synthase activity and the relative immunoblot contents of SP72, SP73 (the constitutive isoform of the SP70 family), and a 75-kDa mitochondrial chaperone (SP75) were subsequently determined. LV and RV did not differ on any measure, and SP73, SP75, and citrate synthase were not affected by training. Cardiac SP72 levels were elevated over fourfold in both ventricles of TM-Tr compared with RV of FW-Sed rats. Despite the animals having run a similar total distance, cardiac SP72 content in FW-Tr rats was not different from that in Sed animals. These data indicate that voluntary exercise training is insufficient to elicit an elevation of SP72 in rat heart and suggest that exercise intensity may be a critical factor in evoking the cardioprotective SP72 response.

Calcium channel blockers inhibit endogenous pyrogen fever in rats and rabbits

1991 ◽  
Vol 71 (3) ◽  
pp. 951-955 ◽  
Author(s):  
J. T. Stitt ◽  
S. G. Shimada
Keyword(s):  
Channel Blocker ◽  
Standard Dose ◽  
Detectable Effect ◽  
Prostaglandin E ◽  
Channel Blockers ◽  
Sprague Dawley ◽  
Endogenous Pyrogen ◽  
Ambient Temperatures ◽  
Antipyretic Activity ◽  
Sprague Dawley Rats

We have previously shown that febrile responses in both rats and rabbits are elicited by the intravenous injection of a semipurified endogenous pyrogen (EP) prepared from human monocytes. We are now presenting evidence that these febrile responses are mediated via activation of Ca2+ channels by EP. The febrile responses of male New Zealand White rabbits and Sprague-Dawley rats to a standard dose of EP were determined at their respective thermoneutral ambient temperatures. The animals were then treated with Ca2+ channel blocker verapamil (7.5 mg/kg iv) 30–60 min before the EP challenge. In every case the febrile response to EP was markedly attenuated after verapamil pretreatment, while administration of verapamil by itself had no detectable effect on body temperature. Another Ca2+ channel blocker, nifedipine (5 mg/kg iv), was shown to possess antipyretic activity in rats also. To localize where in the fever pathway these Ca2+ channel blockers were acting, we investigated the effect of verapamil at the same dose on fevers that were produced by microinjection of prostaglandin E (PGE) directly into the brain. These PGE fevers were unaffected by verapamil pretreatment, indicating that the antipyretic action of Ca2+ channel blockers occurs before the formation of PGE in response to EP stimulation. The most likely locus of action is the activation of the enzyme phospholipase A2, which regulates the production of arachidonic acid from cellular phospholipids in the prostanoid cascade.

Effects of apomorphine and pimozide on temperature regulation during exercise in the rat

1980 ◽  
Vol 49 (3) ◽  
pp. 363-366 ◽  
Author(s):  
C. V. Gisolfi ◽  
F. Mora ◽  
S. Bloomfield ◽  
M. Beattie ◽  
S. Magnes
Keyword(s):  
Oxygen Consumption ◽  
Receptor Agonist ◽  
Heat Dissipation ◽  
Treadmill Exercise ◽  
Anterior Hypothalamus ◽  
Dopamine Receptor Agonist ◽  
Ambient Temperatures ◽  
On Line ◽  
Colonic Temperature ◽  
Dose Dependent

The purpose of this study was to determine the effects of a specific dopamine receptor agonist (apomorphine) and antagonist (pimozide) on thermoregulation when the heat loss pathway was activated by the stress of exercise. Apomorphine or its control vehicle (0.9% wt/vol saline) was injected systemically (0.5, 1.0, 1.5 mg/kg ip) or within the preoptic-anterior hypothalamus (5, 10, 20 micrograms) immediately before the start of treadmill exercise at 21.5 m/min. Colonic, tailskin, and ambient temperatures were recorded each minute. Oxygen consumption was calculated from on-line measurements of percent O2 and CO2. Pimozide injected systemically (0.5 mg/kg ip) had no effect on resting colonic temperature, but caused a significant (P less than 0.05) hyperthermia during treadmill exercise compared to saline controls. Central and systemic injections of apomorphine caused a dose-dependent hypothermia that was blocked by pretreatment with pimozide. Oxygen uptake values during exercise following the central injection of apomorphine were virtually identical to those following the injection of saline, but colonic temperature was significantly (P less than 0.05) lower than saline controls, indicating that the hypothermia observed was not due to a reduction in metabolic rate. These data indicate that dopamine receptors in the preoptic-anterior hypothalamus of the rat participate in the mediation of heat dissipation when the animal is challenged with a heat stress.

Heat acclimation: role of norepinephrine in the anterior hypothalamus

1985 ◽  
Vol 58 (6) ◽  
pp. 1923-1928 ◽  
Author(s):  
J. V. Christman ◽  
C. V. Gisolfi
Keyword(s):  
Preoptic Area ◽  
Treadmill Exercise ◽  
Heat Acclimation ◽  
Tolerance Test ◽  
Chronic Exercise ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Series Of Experiments ◽  
Catecholamine Storage

The hypothesis that anterior hypothalamic (AH) sensitivity to norepinephrine (NE) is altered by chronic exercise in the heat was tested in male Sprague-Dawley rats. Treadmill exercise 6 days/wk for 3 wk at 21 m/min was performed at 23 degrees C (control; C) or at 35 degrees C (heat acclimated; HA), progressing from 20 to 50 min/day in 2 wk. Time for core temperature (Tco) to rise from 39.5 to 40.5 degrees C during a heat-tolerance test after conditioning increased (P less than 0.05) in the HA group. To test for a change in AH sensitivity, the change in Tco to 2-, 5-, 10-, 20-, and 40-micrograms doses of NE injected bilaterally into the AH was determined after conditioning. Dose-response regression lines showed that exercise in the heat increased the slope and shifted the Tco-NE dose relation to the left. In a separate series of experiments on 6 sedentary(s), 10 C, and 10 HA animals, the amounts of NE, dopamine, and 3,4-dihydroxyphenylglycol (DOPEG) were determined by high-pressure liquid chromatography in the AH, median preoptic area (PO), cortex, and cerebellum after 9 wk of conditioning. Results showed that in the PO there was a significant increase in NE and DOPEG in the HA vs. C group and a trend of increasing NE from the S to C to HA groups. The data indicate that exercise in the heat increases NE-induced peripheral heat-dissipating capacity and increases catecholamine storage in the PO.

Hypothyroidism increases serotonin turnover and sympathetic activity in the adult rat

1991 ◽  
Vol 69 (2) ◽  
pp. 205-210 ◽  
Author(s):  
W. N. Henley ◽  
X. Chen ◽  
C. Klettner ◽  
L. L. Bellush ◽  
M. A. Notestine
Keyword(s):  
Recovery Period ◽  
Normalization Procedure ◽  
Sprague Dawley ◽  
Creatinine Excretion ◽  
Adult Rat ◽  
Sympathetic Function ◽  
Sham Surgery ◽  
Sprague Dawley Rats ◽  
Serotonin Turnover ◽  
Colonic Temperature

Adult, male Sprague–Dawley rats underwent surgical thyroidectomy (Tx) or sham surgery. In all three experiments from which data are reported, a 3-week recovery period was allowed. In experiments I and II, baseline measurements of colonic temperature (Tc) and urinary norepinephrine excretion (NE) were obtained, and both variables were monitored daily for the duration of the studies. After baseline measurements, half of each surgical group was given either triiodothyronine (T3) or vehicle injections subcutaneously; in experiment I replacements continued for 1.5 days, while in experiment II T3 replacement continued for 3.5 days. Rats were decapitated at the end of each experiment and serotonin (5-HT) turnover was measured in brainstem. Serotonin turnover in rostral and caudal brainstem was increased with Tx (p < 0.05). Increased turnover in caudal brainstem was normalized by T3 only in experiment II. Similarly, decreased Tc and elevated NE with Tx were normalized in experiment II but not in experiment I. In experiment III, NE measurements normalized on a creatinine excretion basis indicated that increased NE is evident with Tx, irrespective of normalization procedure. Significant correlations between 5-HT in caudal brainstem and metabolic correlates of sympathetic function, concurrent normalization of NE and 5-HT in caudal brainstem, plus work from other laboratories describing sympathoexcitatory serotonergic neurons located in me caudal brainstem suggest that the central and peripheral changes in me hypothyroid rat are causally related.Key words: triiodothyronine, norepinephrine, serotonin, brainstem, metabolism.

Reduction in metabolic heat production during exposure to radio-frequency radiation in the rat

1987 ◽  
Vol 62 (5) ◽  
pp. 1814-1818 ◽  
Author(s):  
C. J. Gordon
Keyword(s):  
Body Temperature ◽  
Metabolic Rate ◽  
Radio Frequency ◽  
Radiation Exposure ◽  
Type System ◽  
Continuous Control ◽  
Sprague Dawley ◽  
Deep Body Temperature ◽  
Radio Frequency Radiation ◽  
Colonic Temperature

The purpose of this study was to assess the ability of the rat to reduce metabolic rate when exposed to deep-penetrating radio-frequency (RF) radiation. Male Sprague-Dawley rats were maintained at an ambient temperature (Ta) of 10 degrees C and exposed to 600-MHz radiation while metabolic rate (MR) was measured by indirect calorimetry. RF radiation exposures were made in a waveguide-type system that permitted the continuous control of specific absorption rate (SAR). SAR's of 2–5 W/kg led to significant reductions in MR when averaged from 30 to 60 min after the initiation of RF radiation exposure. The total decrease in MR during RF radiation exposure accounted for approximately 37% of the total RF heat load. Exposure of another group of rats to the same SAR's at a Ta of 10 degrees C resulted in a significant elevation in colonic temperature. Thus, despite the decrease in MR, heat gain still exceeded heat loss during RF radiation exposure, with a resultant elevation in deep body temperature. In conclusion, in a cold environment the rat exposed to RF radiation decreases its MR. However, the response time and efficiency of the response is not adequate to prevent an increase in body temperature.

Cardiovascular response to acute aquatic and treadmill exercise in the untrained rat

1979 ◽  
Vol 46 (2) ◽  
pp. 302-308 ◽  
Author(s):  
S. F. Flaim ◽  
W. J. Minteer ◽  
D. P. Clark ◽  
R. Zelis
Keyword(s):  
Treadmill Exercise ◽  
Cardiovascular Response ◽  
Regional Blood Flow ◽  
Cardiovascular Effects ◽  
Sprague Dawley ◽  
Hemodynamic Changes ◽  
Radioactive Microsphere ◽  
Sprague Dawley Rats ◽  
Radioactive Microsphere Technique ◽  
Muscle Groups

The cardiovascular effects of acute aquatic (AE) and treadmill (TE) exercise were determined in untrained adult male Sprague-Dawley rats. Animals were exercised to exhaustion or for a maximum of 5 min with either exercise mode and data collected during the last minute of exercise were compared to preexercise rest data. Heart rate and cardiac output increased only with TE; arterial pressure remained stable during both protocols. Regional blood flow was determined by the radioactive microsphere technique. Coronary flow increased only with TE. Skeletal muscle flow, determined in six muscle groups, increased more with TE (97 to 587%) than with AE (-44 to 260%) (flow in the quadriceps group decreased during AE). Flow to the skin and splanchnic regions decreased; cerebral flow increased in both groups. Blood gas data suggest lactic acidosis and hyperventilation only with TE. These data indicate that 1) the cardiovascular effects of acute, exhaustive bouts of AE and TE in the rat are not comparable, and 2) the hemodynamic changes occurring with exhaustive TE in rat, as in man, involve a shunting of blood to the regions of demand and away from the nonessential circulations.

Sign in / Sign up

Export Citation Format

Share Document