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

A hypothermia and rewarming system combining body surface and ventilatory heat exchange is described. The method utilizes body surface heat exchange through conduction, convection, and black body radiation, and ventilatory heat exchange across the lung surface through conduction, convection, and water evaporation. The system consisted of a chamber in which the temperature was maintained at a desired level (+/- 2.5 degrees C) using a refrigeration-heat pump unit. Chamber temperatures during cooling and rewarming were -15.5 +/- 2.7 degrees C and 43.2 +/- 2.3 degrees C, respectively. Inhalate temperatures during cooling were -8.2 +/- 6.5 degrees C and during rewarming they were 41.5 +/- 0.3 degrees C. Helium (100%) was supplied to the chamber, while the animal was ventilated with 20% O2 + 80% He. Under these conditions, the cooling and rewarming rates were 0.33 +/- 0.06 degrees C/min and 0.20 +/- 0.04 degrees C/min, respectively, at 38--21 degrees C. The system provided for rapid cooling and rewarming with no evidence of any untoward effects.
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PMID:An improved method for inducing hypothermia and rewarming. 49 55

We have investigated the ability of three hyperthermic stimuli (PGE2, 5-HT and ACh) to elicit hyperthermia in the Helium-Cold (He-Cold) hypothermic hamster. Hamsters in these conditions are poikilothermic and will passively follow room temperature in a regulated cold room. Animals were injected centrally at AH/POA sites via an indwelling guide tube at body temperatures maintained between 9-12 degrees C. Active sites in the AH/POA were determined prior to the experiment by PGE2 injection. PGE2 injection at an effective AH/POA site immediately reversed the anesthetic induced hypothermia in warm air. Hamsters were induced into hypothermia by the He-Cold induction method and body temperatures were maintained in a 9 degrees C cold room. Colonic temperatures were monitored at 5 minute intervals by a YSI thermistor probe and telethermometer. Central injections of 5-HT (2 micrograms/microliter) and ACh (50 micrograms/microliter) at effective AH/POA sites evoked significant increases in colonic temperature in He-Cold hamsters. PGE2 injections were not different from saline control injections and did not elicit pronounced temperature changes in these animals. Specific blockade of the 5-HT and ACh temperature increases was demonstrated with specific antagonist injections. The results suggest that the central organization of heat-gain mechanisms in the AH/POA is the same as normothermic animals even at temperatures well below those previously investigated.
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PMID:Organization of central hyperthermic mechanisms in helium-cold hypothermic hamsters. 346 74

Helium-cold hypothermic hamsters, colonic temperature (Tc) 7 to 11 degrees C, injected with acetylcholine (ACH) at a preoptic-anterior hypothalamic (AHPOA) site responded with a rise in colonic temperature while remaining in a cold environmental chamber. The He-Cold hamster does not thermoregulate at these body temperatures. In contrast to central ACH-elicited responses, the injection of alpha and beta adrenergic drugs into the systemic circulation of the He-Cold hamster did not elicit a rise in colonic temperature. The data describe a different animal model of rewarming than has previously been described that is under pharmacologic control by the experimenter. The use of exogenous neurotransmitter provides the potential to understand the mechanisms of thermoregulation in deep experimental hypothermia.
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PMID:Induced rewarming by central stimulation in hypothermic hamsters. 405 71

1. Norepinephrine (NE) and serotonin (5-HT) were simultaneously assessed in 4 discrete regions of the brain of the golden hamster. 2. Hypothalamic concentrations of both these amines are reported for the following groups: (1) normothermic controls; (2) heat acclimated; (3) cold acclimated; (4) helium-cold hypothermic; (5) rewarming; and (6) rewarmed. 3. Heat acclimated animals demonstrated approximately 35 and 25% decreases from control values for NE and 5-HT, respectively. Cold acclimated hamsters were not significantly different from controls. Helium-cold hypothermia resulted in approximately a 30 and 20% decrease in NE and 5-HT, respectively, with the latter returning to control values during rewarming. 4. The data provide indirect evidence for the involvement of NE in central pathways involving heat gain and 5-HT in pathways involving heat loss, and are discussed in terms of FELBERG & MYER'S (1964 J. Physiol., Lond. 173. 226-236) bioamine theory of thermoregulation.
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PMID:Brain norepinephrine and serotonin in the golden hamster during heat and cold acclimation and hypothermia. 612 3