Effects of Local Roentgen Irradiation on the Rate of Endogenous-dehydrogenase Activity in the Epidermis of Hairless Mice Studied by Means of a Tetrazolium-reduction Method

Summary Four-hundred-and-forty-one mice from a recessive hairless strain were given local roentgen irradiation on a skin-flap with doses from 2700 to 500 r. The amount of formazan deposited in the epidermis was measured at different time-intervals after irradiation, and the results presented as the ratio between the values obtained in irradiated and non-irradiated areas. A characteristic reaction type was observed with an increase in the deposition of formazan, followed by a period of decrease. The effect was decreasing with falling doses and hardly measurable with 500 r. The findings are interpreted as pointing to some destruction of the cellular respiration. The similarity between this effect and the effect of chemical carcinogens is briefly mentioned.