Irradiation of mouse lungs causes a dose-dependent increase in lung weight

The lungs of Balb/c mice were irradiated with doses of 200 to 1300 rad and excised and weighed three days to 20 weeks later. In all cases the wet weights were increased relative to unirradiated controls. The weight increases were dose-dependent up to 1000 rad. The largest weight increase was 28%. Comparison of the wet and dry weights of irradiated and control lungs indicated that the material responsible for the weight increase was intermediate in water content between normal lung tissue and plasma, whereas the water content of pulmonary edema fluid produced by adrenalin injection was similar to plasma. Protection of the mediastinum during irradiation did not affect the weight increase appreciably.