LATE EFFECTS OF LOW-DOSE WHOLE BODY X-IRRADIATION OF FOUR-DAY-OLD RATS

[摘要] 1. Four-day-old male and female Long-Evans x Sprague-Dawley F1 hybrid rats were exposed to a single total body x-ray dose of 125, 25, 5, and 0 r and then were observed during their entire lifespan for weight changes, signs of morbidity and age at death.2. There was a 10% reduction of life span in the 125 r exposed female rats. None of the male groups showed significant shortening of longevity.3. Mean body weights were consistently lower in both male and female groups exposed to 125 r total body irradiation.4. Female rats exposed to 25 and 125 r attained their maximum weights at a younger age than their non-irradiated controls.5. External tumors appeared earlier in female rats. Tumor incidence was not increased by irradiation in either sex.6. Male parentage influenced the length of life span of progeny to a greater degree than the irradiation exposure at the employed dose-level. The influence of female parentage upon longevity cannot be evaluated in this study.7. Low dose radiation life shortening can only be demonstrated in long-lived strains. Hereditary and radiation life shortening effects are not cumulative under conditions of this study.

[学科分类] 儿科学