Whole body hyperthermia (41-42 degrees C): a simple technique for unanesthetized mice

A technique for accomplishing 41-42 degrees C whole body hyperthermia (WBH) in unrestrained, unanesthetized mice using a simple apparatus is reported. This method combines a radiant heat technology with monitoring of individual rectal temperatures at 10-min intervals. In 66 heating sessions, involving 116 AKR mice and a total of 619 WBH treatments, the mortality rate was less than 1%. Treatment at 41-42 degrees C for periods of up to 120 min were accomplished. Relationships of several variables of mouse temperature-time profiles were studied including (1) initial core temperature, (2) rate of heating, (3) whole body irradiation, and (4) the presence of tumor (transplanted AKR leukemia). Sham treatments produce a consistent temperature-time profile showing about a 1 degree C rise. Between-mouse variability, as well as between-treatment variability in individual animals was estimated. Thermal mapping of the device demonstrates a range from 32-38 degrees C of the air temperature in the zone with the mice to a high of 47 degrees C near to the radiant heating surface at the top of the apparatus.