Radioprotection by pentobarbitone sodium of a murine tumour in vivo

A comparison has been made of the effects of immobilization by either anaesthesia or physical restraint on the local control of mouse tumours at 80 days. The effect of rendering the tumours fully hypoxic (by occlusion of their blood supply) was also studied, as was the effect of immobilization procedures on the tumour temperatures. Pentobarbitone sodium had an even larger radioprotective effect than that of clamping of blood supply to the tumour. A progressive drop in tumour temperature over the experimental period was observed in the anaesthetized mice. The use of pentobarbitone sodium for restraining animals during radiobiological studies should therefore be avoided. Physical restraint systems designed to create low levels of stress are to be preferred. (U.K.)