Effects of pentobarbital on temperature and heart rate of rats subjected to cold

¹ Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia

A study at 5 C was made of body temperature and heart rate after a standard dose of sodium pentobarbital in normal, thyroidectomized, and hypermetabolic rats before and after subjection to 5 C for 46 hr. It was found that after subjection to cold in the normal rats, the body temperature and heart rate in some animals had more ability to recover after the barbiturate than in rats without previous exposure to cold. There was no ability to recover in the thyroidectomized animals either before or after subjection to cold. Most of the normal and thyroidectomized rats either with or without previous exposure to cold given sodium 3,3',5-l-triiodothyronine (T-3) had recoveries after the barbiturate. Some rats given T-3 and subjected to cold had a primary fall in temperature and heart rate that was followed by recovery and then a secondary fall.