[Role of a decrease in the body's heat content on the thermoregulatory reaction of the vessels of the external ear]

At the constant ambient temperature 28--30 degrees C the rabbit ear vessels were dilated and their temperature was 34.8/0.1 degrees C. Administration of the 23--29 degrees water into the stomach entailed thermoregulatory constriction of the ear vessels within 15--25 min. The response occurred at various combinations of temperature changes in different parts of the body. The heat content of the rabbit body, as calculated by the blood temperature in the aorta arc, reduced by 266.3 +/- 26.2 cal/kg at the beginning of the response. The decrease in the organism heat content seems to serve as a signal for occurrence of a corresponding thermoregulatory response.