CARDIOVASCULAR EFFECTS OF MILD SURFACE COOLING.
Final rept., Nov 64-Mar 65.
ARCTIC AEROMEDICAL LAB FORT WAINWRIGHT ALASKA
Pagination or Media Count:
The cardiovascular effects in normothermic dogs cross-circulated with mildly hypothermic dogs were studied in animals that were warm and cold acclimatized. By this technique it was possible to physiologically dissect the neural responses from the humoral or metabolic factors involved. The cardiac output, limb blood flow, arterial pressure and heart rate were measured in normothermic dogs at the time of each 0.5C drop in rectal temperature of dogs that were rendered mildly hypothermic by surface cooling, and at each 0.5C increase in rectal temperature during rewarming. Acute surface cooling of warm-acclimatized dogs liberated specific metabolites andor neurohumors that had a profound cardiovascular effect on cross-circulated normothermic dogs. In similar experiments on cold acclimatized animals, this effect was not observed. It was concluded that cold acclimatization depleted or shifted the cardiovascular threshold response to these metabolites andor neurohumors. Author
- Anatomy and Physiology