Serum glucose, serum free fatty acids and adipose tissue lipids after fatal hypothermia of cold acclimatized, reserpine or propranolol treated guinea-pigs.

Surviving ability in frost (-20 degree C) was studied in cold acclimatized guinea-pigs given either reserpine, propranolol or saline. Survival time, rectal temperature at death, serum glucose, serum FFA and triglycerides in the interscapular adipose tissue were determined. Rectal temperature was highest in the reserpine group, in the same animals that endured the frost the shortest time. The survival time had decreased by about a half of that in the controls. Propranolol treatment decreased the living time only slightly. The fact that serum glucose remained high in the reserpine treated animals was obviously related to the short survival time. In the propranolol group glucose values were somewhat higher than in the control group (saline-animals). Reserpine seemed to have inhibited the release of FFA in the warm-acclimatized animals as interpreted from the low serum values. On the other hand, FFA were rather high in the cold-acclimatized reserpine animals. The blocking effect of reserpine reflected also in the higher contents of triglycerides in the adipose tissue both in cold-acclimatized and warm-acclimatized animals. Propranolol prevented slightly the depletion of the triglycerides. Amount of total lipids in the adipose tissue was lower in the cold-acclimatized animals than in the warm-acclimatized ones because of the change of the type of the adipocytes from unilocular to multilocular. The results corroborated the importance of FFA for longer survival in severe cold. Sensitization to reserpine seems to develop during cold-acclimatization. It calls attention to a possible hazard of reserpine treatment in cold environment.