[Variability of the dose effect in the radio-biologic experimentation on animals. Third communication: Influence of breed, sex, age as well as radiation dose on body weight and survival time in days after whole-body irradiation of Wistar and Siv-50 rats (author's transl)].

After a whole-body irradiation of Wistar and Siv-50 rat males and females with 600 to 900 R, the survival times and the development of weight of the irradiated animals were determined and compared. The development of body weight was influenced by the dose administered as well as by age, sex and breed of the animals. Furthermore, the weight curves showed also characteristic analogies. During a period of 30 days after the irradiation, there are generally two phases with a considerable weight loss which are both accompanied by a reduced absorption of drinking-water and the appearance of a gastrointestinal and hemopoietic irradiation damage as well as the resulting activity increase of the pituitary gland and the cortex of the suprarenal gland. The weight recovery occurring after sublethal radiation doses is also influenced by the administered dose and the age of the animals. The dropping weight curves of dying animals are equally dependent on the administered dose. With regard to the survival time in days in dependence upon the administered dose and the age of the animals, the authors proved that the survival time of the finally dying animals becomes longer as their radioresistance increases. During the last phase of the 30 days' experimentation, females show a markedly increased death rate whereas males seem to have continually better survival chances when they are still alive at the last phase.