The effect of body temperature on the hypoxic fraction in mouse tumours

General anaesthesia as well as mechanical restraint of animals, which is necessary to allow precise local irradiation of mouse tumours, is associated with a rapid drop in body temperature if no special precautions are taken to prevent it. This drop in body temperature leads to an increased sensitivity of the tumour to normoxic irradiation which, in the reported case, may be due to a decrease in the hypoxic fraction from about 20% to about 4% as a result of decreased oxygen consumption and increased tumour perfusion.