• Partitional calorimetry was performed on burned rats with and without excision of the adrenal medullae; animals were housed at ambient temperatures of 20 and 28 C. Rates of excretion of urinary nitrogen were determined for the 12 hours before calorimetry runs. Covering the burn wound with polyethylene returned the evaporative heat loss to normal and resulted in a corresponding decrease in the rate of heat production. Excision of the adrenal medullae resulted in chronic hypothermia of burned rats housed at 20 C. The highest rate of excretion of urinary nitrogen occurred in burned rats with intact adrenal medullae housed at 20 C; this excretion rate was significantly reduced when similar animals were housed at 28 C. The net effect of preventing evaporative heat loss from the wounds of burned rats is the same as that of reducing dry heat loss by elevation of the ambient temperature. Both result in a reduction in the rate of heat production.
(Arch Surg 111:181-185, 1976)