The effect of prazosin pretreatment on hyperthermia produced by noradrenaline in rabbits.

1. Hyperthermia produced by noradrenaline (NA) was accompanied by increased metabolic rate and vasoconstriction of ear skin vessels and a fall in evaporation heat loss. 2. Prazosin (PRA), administered as a single injection, decreased of hyperthermia elicited by NA mainly of attenuation the processes concerned with the heat production and increased of heat loss from respiratory tract and ear skin surface. 3. PRA administered in a 3 hr infusion did not only produce an abolishment of NA-induced hyperthermia but also exerted a hypothermizing effect. 4. PRA introduced intracerebroventricularly also induced a decline in core temperature, inhibiting the metabolic rate stimulated by this amine. 5. These results seem to suggest that NA-caused hyperthermia may be controlled through central adrenergic structures, which are effectively blocked by PRA. Besides, we have presented one more proof concerning the antihyperthermizing activity of PRA and its central point of activity catch.