Studies on the Role of Regional Heterothermy in the Energy Balance of Selected Arctic Mammals.

The influence of an infusion of plasma from a hibernating mammal into an awake cold stressed mammal is being investigated at the Animal Research Facility, Naval Arctic Research Laboratory, Barrow, Alaska. Such plasma contains hibernation trigger substance which may affect a recipients thermoregulatory mechanisms. Plasma was collected from hibernating arctic marmots, Marmota broweri, and infused into woodchucks, Marmota monax. The recipient woodchucks were then subjected to acute cold stress 0 C, 12 hours. Multiple tissue temperatures were monitored by means of implanted thermocouples. Data have not yet been subjected to computerized analysis, however visual inspection of the data reveals no obvious difference between control and experimental groups. During cold exposure heart rate increased from 110-130 beats per minute to the 140-170 range. Regional heterothermy is evident during cold exposure with tissues varying by as much as 6 C within an animal. Of the monitored tissues axiliary brown fat is nearly always the warmest followed by anterior muscle, posterior muscle and the subcutaneous areas. Studies are continuing in this area utilizing an increased volume of hibernation plasma.