Effects of sodium acetylsalicylate on thermoregulatory responses of rats to different ambient temperatures

The effects of intraperitoneal administration of sodium acetylsalicylate (aspirin) on thermoregulatory responses (T_a) of 15, 22 and 29°C were assessed. Intraperitoneal administration of aspirin produced dose-dependent hypothermia at both 15 and 22°C. The hypothermia was brought about by cutaneous vasodilation (as indicated by an increase of the tail and foot skin temperatures). However, in the heat (29°C), i. p. administration of the same amount of aspirin produced no change in rectal temperature, since the thermoregulatory responses were unaffected by aspirin application at this T_a. Thus it appears that aspirin increases heat loss and leads to hypothermia in rats.