Ultrastructural findings in the murine Nonciliated Bronchiolar Cells (NCBC) after subacute inhalation of lead acetate

Abstract

Air pollution is an important health problem in some countries. For Mexico City, repeatedly high levels of some metals including lead (Pb) have been reported. Since there is no relevant information, we used an inhalation model to identify the possible lung cell damage after exposure of animals to Pb. We used thirty CD-1 male mice that were inhaling (for 1 hour) aerosolized lead acetate 0.1M, three times per week during two weeks. Mice were sacrificed by cervical dislocation on days 1, 3, 5, 7, 10 and 15 after the last Pb exposure. Their lungs were fixed by intratracheal instillation of glutaraldehyde. Lung tissue for morphological observation and metal concentration was sampled. In the exposed mice, on days 3 and 5 changes in the nonciliated bronchiolar cells appeared. Whorl-like structures were present in the cell apex. These structures compressed other organelles. On day 5 after the final inhalation, the structures increased in size, and by day 10 they disappeared. After the last inhalation, the metal concentration in the lung tissue continuously decreased until day 7 when no more metal was detected. It was evident that the contact of the NCBC with Pb produces changes in the morphology of these cells. The metal concentrations in the lung decreased when the exposure ended. This finding supports the assumption that Pb is not accumulated in lung tissue. As a consequence, the cellular modifications decreased and began their way to morphological recovery.