Immunohistochemistry, rat. (A-C) Large airways. (A) Epithelial cells (arrows) and cells of the lamina propria were immunoreactive for cav-1α. The labeling of the endothelial cells of capillaries (c) in the lamina propria was stronger compared to that of the epithelium. (B) Anti-cav-1αβ antibody labeled the same cell types as the anti-cav-1α antibody (arrows), however, with stronger intensity of the labeling in the epithelium compared to that in the lamina propria and the smooth muscle cells. (C) Epithelial cells (arrows) as well as cells of the lamina propria and smooth muscle cells were immunoreactive for cav-2. (D-F) Small airways, bronchioli (br). Endothelial cells and type I epithelial cells of the surrounding alveoli were immunoreactive for cav-1α, cav-1αβ and cav-2. No immunoreactivity was detected in the bronchiolar epithelium. Epithelium = e, smooth muscle cells = m, lamina propria = lp.