A NOTE ON METABOLIC EFFECTS OF SUSTAINED HYPOTHERMIA IN RATS

Hypothermia was induced in non-fasted, female rats by placing animals in individual, cylindrical screen cages under crushed ice until a rectal temperature of 15 °C was attained. No anaesthetic or artificial ventilation was provided. Hypothermic animals were sacrificed after 0, 30, and 60 minutes' maintenance at this rectal temperature and metabolites were measured in blood and liver. It was observed that, as previously reported, hypothermia caused increases in blood packed cell volume, glucose and lactic acid levels, and plasma levels of inorganic phosphorus and total ketones. Maintenance of hypothermia for 30 or 60 minutes either caused no further change or accentuated the changes observed initially in these metabolites. Liver glycogen level decreased significantly after 30 minutes but returned to an almost normal level at 60 minutes. From these observations it is concluded that attainment of a "steady state" condition of hypothermia in non-fasted rats does not alter the pattern of metabolic changes observed in acute hypothermia of short duration.