The effects of salicylate on temperature regulation in the rabbit.

1. A stable pyrexia has been produced in rabbits by intravenous injection of leucocyte pyrogen followed by a continuous infusion.2. Intravenous sodium salicylate, given 4 hr after the start of pyrogen infusion, induced rapid and progressive defervescence. The rate of fall of temperature was dose dependent.3. Intravenous injection of sodium salicylate had no effect on the temperature of afebrile rabbits.4. The intraventricular injection of small doses of sodium salicylate, given 4 hr after the start of a pyrogen infusion, caused a rapid, dose-dependent defervescence, but had no significant effect on the temperature of afebrile rabbits.5. Salicylates exert at least part of their antipyretic activity through an action on the central nervous system.