Abstract
Summary
All three groups of hamsters were exposed to a cold temperature of —6° to —8°. Group I served as a control; Group II were thyroidectomized by surgery; and Group III were thyroidectomized by 131I. Exposure to cold causes a significant increase in oxygen consumption and a decrease in body weight of all 3 groups. Animals in Group I and II survived for more than 9 days; however, 68% of the animals in Group III died within 72 hours after exposure to cold. The plasma PBI in Group II was lower than in Group I and higher than in Group III. This suggests that the hamster likely has ectopic thyroid tissue which enhances survival of thyroidectomized animals. A comparison of control and surgically-ThX animals suggest that the known increases in TSR at cold temperatures are not significant in survival to extreme cold.
Further investigations should test the value of thyroxine replacement of survival of the radio-thyroidectomized animals and a comparison on propyl thiouracil and thyroxine-supplemented intact animals when exposed to extreme cold.