Relative distribution of AuNP (singlets, small or large agglomerates) in lung tissue. From 0 h to 24 h after aerosol inhalation, the percentage of lung-retained AuNP decreased on the epithelial surface and increased in macrophages in both animal groups, while in alveolar type I epithelial cells, an increase of AuNP was observed in Scnn1b-Tg mice only. At 0 h, the percentage of AuNP was highest in macrophages of Wt mice, whereas in Scnn1b-Tg mice, the highest percentage of AuNP were registered on the epithelial surface. The percentage of AuNP attached to lining layer material (surfactant) and internalized by alveolar type II epithelial cells was low (less than 5%) in both animal groups and remained unchanged between the two time points studied. Data are presented as mean values of n = 2 animals per genotype and time point.