PERFORMANCE OF SMALL MAMMALS AT LOW BODY TEMPERATURES.
GEORGETOWN UNIV WASHINGTON D C DEPT OF BIOLOGY
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The effect of low body temperature on trained performance was determined, and the causes of performance failure at critical body temperature levels were analyzed. The behavioral analysis included heat reinforcement and shock escape operant procedures. The critical body temperature for performance for the hypothermic rat was found to be 23 - 25C, several degrees C above the level of complete motor collapse. The hamster, a hibernator, showed greater variation in its hypothermic response and failed to perform at lower body temperatures than the rat. Physiological studies were begun on chronically cannulated unrestrained rats during progressive hypothermia and during rewarming. Blood pressures and heart rate were significantly different at certain corresponding temperature ranges during cooling and rewarming phases. Chronically cannulated but anesthetized control rats had consistently lower systolic and diastolic pressures and heart rates during the entire cooling process. A supplementary study on Dimethyl sulfoxide administered IP 3 or 6 gkg in saline revealed a significant temperature regulation disturbance at ambient temperatures of 1, 15 and 25C. Exposure of DMSO treated subjects to 1C resulted in deep hypothermia for all at 15C one -third cooled to ambient temperature. At 25C, there was a body temperature depression of 3.6C. It appears, however, that the critical body temperature for performance was not affected by these doses of DMSO. Author
- Anatomy and Physiology
- Stress Physiology