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Query: UMLS:C0020672 (hypothermia)
 17,327 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of cardiopulmonary bypass (CPB) on myocardial extravascular water (MEW) was evaluated with crystalloid and colloid hemodilution. Heart water was measured gravimetrically and by the double-indicator and thermal methods. CPB without hemodilution resulted in a 5.7 per cent increase in the wet : dry weight ratio of the left ventricle obtained by desiccation to stable weight. CPB with colloid hemodilution to a hematocrit of 10.7 +/- 0.4 per cent resulted in a 5.4 per cent increase in the wet:dry weight ratio. Crystalloid hemodilution to a hematocrit of 9.5 +/- 0.8 per cent resulted in a marked increase in myocardial water with a wet:dry weight ratio 30.3 per cent greater than the controls. Hypothermic (22 degrees C.) crystalloid hemodilution resulted in a 37.4 per cent increase in the wet:dry weight ratio. MEW was also measured by the double-indicator method with Evans blue dye and tritiated water. This method measured 85 per cent of the gravimetrically measured water. Although it indicated the increase in heart water in the crystalloid group, it proved less reliable in the measurement of MEW in this dynamic situation. The thermal heart water was also measured with an impedance and thermistor-bearing catheter similar to that used to measure thermal lung water. This proved ineffective in measuring heart water. Colloid hemodilution was thus found to prevent the development of myocardial edema which occurred with crystalloid hemodilution (p less than 0.01) with and without hypothermia. These findings support the addition of colloid to the hemodilution prime used for cardiopulmonary bypass.
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PMID:The effects of cardiopulmonary bypass with crystalloid and colloid hemodilution on myocardial extravascular water. 83 Oct 3

The performance of three widely used rat lines (Sprague-Dawley, Wistar, and Long Evans hooded) were evaluated in behavioral test systems that are sensitive to benzodiazepines. The in vivo effects of flunitrazepam and the brain [3H]Ro 15-1788 binding were determined and compared in these rat lines. The behavioral end points evaluated in this study were anxiolysis, measured using the automated elevated plus-maze; sedation by modification of locomotor activity; hyperphagia following food deprivation; protection for pentylenetetrazol-induced convulsions; and hypothermia. There were comparable results in the hypnotic, hypothermic, anticonvulsant, and feeding tests in these lines following flunitrazepam administration. However, the behavior of the Long Evans hooded rat was most amenable to the detection of drug-induced changes in the anxiety test. There was no difference in the maximum number of binding sites (Bmax) or the affinity (Ki) of the Ro 15-1788 or flunitrazepam binding in either the cerebellum or whole brain (minus cerebellum) in the three rat lines as determined by the competitive binding against [3H]Ro 15-1788. Thus, while these rat lines exhibited similar behavioral profiles in most tests the modest differences in the baseline responses and the ability to detect anxiolysis at lower doses of flunitrazepam observed with Long Evans hooded rats makes them particularly suited for these types of studies.
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PMID:Comparison of behavioral and central BDZ binding profile in three rat lines. 136 Jan 63

In hypothermic rats with acute hypertension induced by intravenous injection of adrenalin, regional changes in blood-brain barrier permeability to macromolecules were investigated using Evans blue as indication. Evans blue albumin extravasation was determined as a macroscopic finding and a quantitative estimation with a spectrophotometer using homogenized brain to release the dye was also performed to evaluate the macroscopic findings. Five groups of rats were studied: Group I: normothermia + acute hypertension; Group II: hypothermia + acute hypertension; Group III: control hypothermia; Group IV: normothermia + hypotension; Group V: control normothermia. The rats were anaesthetized with diethyl-ether. Body temperature was lowered by submerging anaesthetized animals in an ice water bath. The colonic temperature was reduced to 20 +/- 1 degrees C. During adrenaline-induced acute hypertension the mean arterial blood pressure increased in both normothermic and hypothermic animals. Blood-brain barrier lesions were present in 40% of normothermic rats, and 60% of hypothermic rats after adrenaline-induced hypertension. Mean value for Evans blue dye in the whole brain was found to be 0.530 +/- 0.202 mg% in the normothermic rats and 0.752 +/- 0.256 mg% in the hypothermic rats during adrenaline-induced hypertension. This difference between normothermic and hypothermic rats was found to be statistically significant (P less than 0.01). Our results showed that the extravasation of Evans blue albumin was most pronounced in the brains of hypothermic rats compared to normothermic rats after adrenaline-induced acute hypertension.
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PMID:Influence of profound hypothermia on the blood-brain barrier permeability during acute arterial hypertension. 151 50

This study examined the relationship between inhibition of cholinesterase activity (CA) and thermoregulatory response in the rat following exposure to the organophosphate (OP), diisopropyl fluorophosphate (DFP). Male Long-Evans rats were injected with DFP dissolved in peanut oil in doses ranging from 0 to 1.5 mg/kg (s.c.). Colonic (Tcol) and tail skin temperature (Ttail) were recorded at 0, 1, 2 and 3 h post-injection. At 3 h post-injection the rat was sacrificed and a blood sample was taken by cardiac puncture and analyzed for CA. There was a biphasic dose effect of DFP on Tcol with slight but significant elevation in Tcol in the dose range of 0.01-0.5 mg/kg and a significant depression in Tcol at doses of 1.0 and 1.5 mg/kg. There was a dose-dependent fall in CA with DFP administration in the erythrocyte, plasma, and whole blood fractions. Hypothermia was associated with 80-87% inhibition in CA, whereas the elevation in Tcol was associated with 20-70% inhibition in CA. DFP also elicited significant elevations in Ttail. Overall, the data fail to demonstrate any clear relationship between inhibition of blood CA and thermoregulatory response following exposure to DFP. However, the elevation in Tcol following relatively low doses of DFP may be of relevance to the frequently reported symptom of fever in humans exposed to OP agents.
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PMID:Relationship between cholinesterase inhibition and thermoregulation following exposure to diisopropyl fluorophosphate in the rat. 175 22

A Functional observational battery (FOB) was utilized to provide a semiquantitative description of the hyperreactivity, excitability, and debilitation produced by amitraz. Adult male Long-Evans rats were administered either vehicle or 10, 25, 50, 100, or 200 mg/kg amitraz ip. They were tested with the FOB immediately before dosing, at 1 and 4 hr, and at 1, 2, 4, and 8 days after dosing. Higher doses (100-200 mg/kg) produced increased reactivity to manipulation, tenseness, and aggression. Most or all doses produced depressed arousal and rearing activity, hypothermia, body weight loss, and autonomic changes including ptosis, chromodacryorrhea resulting in facial crustiness, loss of the pupil reflex, and decreased defecation. Altered gait and decreased landing foot splay were also produced by amitraz. For the most part, effects of lower doses (10-50 mg/kg) were reversible by 2 to 4 days after treatment. In the higher dose groups, however, signs of toxicity were evident, and in some cases even more prominent (e.g., handling hyperreactivity), 8 days after a single dose of amitraz. The FOB thus provided a semiquantitative description of the magnitude and time course of many features of the amitraz toxicity syndrome.
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PMID:Investigations of amitraz neurotoxicity in rats. IV. Assessment of toxicity syndrome using a functional observational battery. 191 81

Experiments were designed to assess the mechanisms of diisopropyl fluorophosphate (DFP)-induced changes in thermoregulation of the rat. In one study, male rats of the Long-Evans strain were injected with DFP (s.c.) at doses ranging from 0 to 2.0 mg/kg while maintained at an ambient temperature (Ta) of 20--24 degrees C. Body (Tb) and tail skin (Tt) temperatures were recorded for 5 h post-injection. DFP doses of greater than or equal to 1.0 mg/kg resulted in significant decreases in Tb lasting up to 5 h and increases in Tt lasting up to 1 h post-injection. In a second study, metabolic rate (MR), evaporative water loss (EWL), motor activity (MA), Tb, and Tt were measured at 2 h post-injection of 0, 0.5, 1.0, and 1.5 mg/kg DFP (s.c.) at Ta values of 10, 20, and 30 degrees C. DFP treatment resulted in hypothermia at all three Ta values, but the effect was attenuated at 30 degrees C. MR was significantly reduced at a Ta of 20 degrees C following 1.5 mg/kg, unaffected by DFP at a Ta of 30 degrees C, and stimulated at 10 degrees C following 0.5 mg/kg DFP. EWL was significantly elevated at 30 degrees C following 1.5 mg/kg DFP. MA was significantly reduced following greater than or equal to 1.0 mg/kg DFP at 20 and 30 degrees C and 1.5 mg/kg at 10 degrees C. Tt was elevated and reduced by DFP at Ta values of 30 and 10 degrees C, respectively. In a third study, rats were injected with DFP and placed in a temperature gradient for 1 to 2 h post-injection while selected Ta and Tb were monitored. While both control and DFP-treated rats remained in the cool end of the gradient, rats administered DFP at doses of 1.0 and 1.5 mg/kg were significantly hypothermic. It was also found that Ta values of 10, 20, and 30 degrees C had no effect on DFP-induced inhibition of cholinesterase activity of plasma and erythrocyte fractions of whole blood. Overall, these data support the hypothesis that acute DFP may lower the set-point for the control of body temperature in the rat and demonstrates that the toxicity of DFP is modified by changes in Ta.
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PMID:Acute effects of diisopropyl fluorophosphate (DFP) on autonomic and behavioral thermoregulatory responses in the Long-Evans rat. 201 60

Differences in alcohol consumption and in sensitivity to the effects of ethanol were investigated in four outbred rat strains: Fischer 344, Long-Evans, Sprague-Dawley and Wistar. Alcohol consumption was measured in all four strains in three separate subgroups for each strain, using three different concentrations of ethanol (5, 10 and 20% v/v). An intermittent forced alternate-day ethanol presentation procedure (ethanol as the sole fluid for one day followed by only water the next day), as well as a two-bottle choice paradigm, were employed for this purpose. Ethanol-induced hypothermia and motor impairment (tilting plane test) were used to assess sensitivity. Significant differences in alcohol consumption were found among these strains. The Long-Evans strain consumed the highest and Fischer 344 the lowest amount of ethanol. Wistar and Sprague-Dawley were intermediate. However, the strains did not differ in sensitivity to ethanol. Similarly, determination of sensitivity to ethanol on day 0 in separate groups of these four strains (same age and weight, and obtained at the same time from the same supplier) did not reveal graded differences in sensitivity (hypothermia and motor impairment) corresponding to differences in alcohol consumption. These results suggest that sensitivity does not correlate with alcohol consumption.
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PMID:Comparison of sensitivity and alcohol consumption in four outbred strains of rats. 222 46

While methanol neurotoxicity has been studied for decades, there are very few data available on the thermoregulatory effects of methanol exposure. This paper will present the results of three studies designed to assess the effects of methanol on body temperature and behavioral thermoregulation in Fischer and Long Evans rats. The first study measured the onset of body temperature changes following methanol exposure. Following gavage of 3 g/kg methanol (20% w/v in saline), brain temperature (Tbr) of Fischer rats decreased 1.5 degrees C within 35 min. A similar volume of saline led to transient increases in Tbr. A second study assessed the time course of changes in body temperature by measuring colonic temperature (Tc) hourly following IP injection of saline or 1 or 3 g/kg methanol. The highest dosage of methanol caused a significant hypothermia in both Fischer and Long Evans rats. The hypothermia reached its nadir in both strains at 1-2 hours and partially recovered within the 6 hour experiment. The third study measured the effects of methanol on behavioral thermoregulation. Fischer and Long Evans rats were gavaged with saline or 1-3 g/kg methanol and placed in a temperature gradient. After 90 min in the gradient, rats of both strains which received 2 or 3 g/kg methanol had a significantly lower Tc than control rats. However, the methanol-treated rats remained in the cool end of the gradient and did not prevent the hypothermic effect of the alcohol. The absence of an observed effect on behavioral temperature selection suggests that methanol may interfere with thermal sensation.
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PMID:Thermoregulatory effects of methanol in Fischer and Long Evans rats. 231 59

Brain stem auditory evoked potentials (BAEPs) were studied as a criterion for evaluating hypothermic effects on the brainstem in rats. Eleven adult male Long-Evans rats were cooled slowly from 37 degrees C to 25 degrees C by an ice pad. BAEPs were recorded at intervals of every 1 degree C of change, and both central and peripheral acoustic conductions were assessed. As the body temperature decreased, latencies significantly increased, with the most prominent effect at the higher brainstem level. Interpeak latencies were prolonged also, while the reverse occurred with warming. These data agree with previous studies in other animals and men. However, during analysis of the effects of hypothermia on the brain stem auditory pathway, it was shown that these hypothermic effects were equally distributed throughout the whole pathway in the present study, rather than being emphatic in the proximal portion only. Greater prolongation of latencies in the proximal portion was caused by a cumulative effect from the distal peaks. Recovery was attained completely after rewarming and subsequent survival. Under extreme hypothermia, BAEPs disappeared gradually with apnea and cardiac arrest; however, resuscitation and rewarming saved the rats. In addition to wishing to make conventional observations, the present study sought to recognize the section of the acoustic pathway most sensitive to hypothermic effects and interpret the outcome after hypothermia treatment.
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PMID:Alterations of brain stem auditory evoked potentials in hypothermia. 234 52

Triadimefon is a widely used systemic fungicide, yet there is little published information on its effects in mammals. This study describes the effects of triadimefon in male and female rats using a functional observational battery (FOB), motor activity (measured in a figure-eight maze), and operant performance (responding under a fixed-interval 3-min schedule). For the FOB, Long-Evans hooded rats were tested immediately before dosing and 0.5, 4, 24, and 48 hr after IP dosing with either vehicle, 30, 100, or 300 mg/kg triadimefon. Prominent effects of triadimefon (100 and 300 mg/kg) included increased arousal, stereotypies involving repetitive sniffing, head bobbing, and pacing, and self-mutilation. Dose-related handling-induced convulsions, changes in reflexes and sensory reactivity, hypothermia, and body weight loss were also significant findings. Doses of 30, 75 and 150 mg/kg triadimefon increased figure-eight maze activity whereas 300 mg/kg decreased activity. Habituation of activity during the session as well as the spatial distribution within the maze were also affected by triadimefon. Overall rates of responding maintained by fixed-interval milk reinforcement were increased at 30 and 56 mg/kg, and decreased at 100 and 200 mg/kg. Responding within the 3-min fixed-interval was also affected, with low rates normally occurring early in the interval markedly increased. These effects on operant performance were similar to those seen following d-amphetamine, and were attenuated by pretreatment with chlorpromazine (0.5 mg/kg). On many measures, female rats appeared to be somewhat more sensitive than males. Recovery was evident in some measures the day after dosing, but the effects of high doses (greater than or equal to 100 mg/kg) were typically prolonged (several days). Thus triadimefon produced a unique neurotoxic syndrome which is similar in many aspects to that produced by CNS stimulants.
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PMID:Neurobehavioral effect of triadimefon, a triazole fungicide, in male and female rats. 275 25


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