Serial changes in N-isopropyl-p[I-125]-iodoamphetamine in mouse lung observed with a confocal laser scanning microscope

Serial changes in N-isopropyl-p[I-125]-iodoamphetamine (I-125-IMP) in mouse lungs were observed with a confocal laser scanning microscope. Male mice w ere intravenously injected with I-125-IMP and subjected to autoradiographic procedures 20 minutes, and 3 and 24 hours after injection. Differential in terference contrast (DIC) images and confocal images were obtained with a c onfocal laser scanning microscope, and superimposed images were evaluated. Large numbers of silver grains were observed in the interstitium, bronchiol es, and alveolar sacs 20 minutes after the injection, and lamellar distribu tion of the grains was observed on the ciliary surface. The numbers of silv er grains in the interstitium and bronchioles had decreased 3 hours after t he injection of I-125- IMP, but the numbers of silver grains in the alveola r spaces had not. Although small numbers of silver grains remained in both the bronchioles and alveolar sacs 24 hours after the injection, most of the m had washed out. Confocal laser scanning microscopy is considered to be a useful procedure f or studying the distribution of radioisotopes by microautoradiography, beca use it allows clear autoradiographs to be obtained in which tissues and sil ver grains are perfectly matched and all silver grains are in focus.