Effect of beta-radiation on mitotic activity in the skin of the young rat.

Ionizing radiation affects the metabolism of the nucleic acids (1). The synthesis of deoxyribonucleic acid (DNA), measured by the incorporation of a tracer, is consistently depressed (2) while the response of ribonucleic acid (RNA) is quite variable (3). Since most studies of radiation effects on metabolism have been done with extremely high doses of whole-body x-radiation, the results may be complicated (a) by tissue destruction in the target tissue and (b) by secondary effects from other organs and tissues which have been irradiated simultaneously. These complications might be eliminated if such a study were carried out on mammalian skin exposed externally to a pure beta source at a dosage below that which would produce a morphological change, e.g. an inhibition of mitotic activity (4). This paper describes a technic for exposing newly born rats to an external beta source (P32) and reports the effects of various doses on the mitotic rate of cells in the hair follicles and epidermis.