Changes in the Cardiovascular System Following Total Body X-Irradiation

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Abstract
The cardiovascular system of the rat has been studied by both chemical and physiological methods following total body x-irradiation with: a) a single dose of 700 r (an ld50 dose) and b) chronic doses of 100 r/month or 200 r/month for a 7-month period. Histological changes in the heart were absent. Marked chemical and physiological changes suggest, however, that some type of heart failure may be an important factor in the causation of radiation death. In the first 10 days after 700 r, there were: a) marked decreases in deoxyribonucleic acid and actomyosin concentrations in the heart, b) an edema of the heart and lung, c) an increased peripheral venous pressure, d) electrocardiograph changes (including a progression of changes in rhythmicity), and e) a change in the mechanical action of the heart. These effects were most pronounced at the ld50 death period. Chronic irradiation with 100–200 r/month resulted in similar electrocardiographic changes. The heart and testes were the two tissues whose weights were most sensitive to chronic radiation. Changes in the vascular system following 700 r are described in terms of alterations in tissue Evans blue space. In the heart there is a 30–50% increase in plasma volume from 6–10 days after x-ray.