Abstract
Mice were exposed to plutonium dioxide (PuO2) aerosols 2 weeks before or after urethan injection. Both exposures reduced the number and size of adenomas. The incidence of arrested metaphases showed no consistently significant differences between plutonium-exposed and mock-exposed animals. The results are discussed in relation to recent electron microscopic evidence of degenerative changes in the type II epithelial cells of the mouse lung following PuO2 inhalation. It is concluded that damage at the cellular level may account for the observed reduction in growth of pulmonary adenomas in mice whose lungs contained plutonium particles.
Highlights
The results are discussed in relation to recent electron microscopic evidence of degenerative changes in the type II epithelial cells of the mouse lung following PuO2 inhalation
Animals were divided into 4 age-matched groups, each of wrhich contained 57 animals in Experiment 1 and 26 in Experiment 2, the treatments being as follows: Experiment 1.-(a) Plutonium inhalation followed by urethane (PU); (b) plutonium inhalation followed by saline (PS); (c) mock inhalation followed by urethane (MU); (d) mock inhalation followed by saline (MS)
Experiment 2.-(a) Urethane followed by plutonium inhalation (UP); (b) saline followed by plutonium inhalation (SP); (c) urethane followed by mock inhalation (UM); (d) saline followed by mock inhalation (SM)
Summary
The results are discussed in relation to recent electron microscopic evidence of degenerative changes in the type II epithelial cells of the mouse lung following PuO2 inhalation. It is concluded that damage at the cellular level may account for the observed reduction in growth of pulmonary adenomas in mice whose lungs contained plutonium particles. THE INCIDENCE of pulmonary adenomas in urethane-treated mice is decreased by large doses of whole-body X-irradiation (Foley and Cole, 1963; Bartlett, 1970). Inhalation of 239PuO 2 particles 2 weeks before urethane injection led to a significant decrease in tumour incidence (Brightwell and Heppleston, 1973). The proliferative response in the tumours has been examined as well as the effect of Pu inhalation after uretbane administration
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