Figure 5

Immunohistochemical localization of OCTs in murine bronchi. OCT1-immunolabelling is localized to the apical membrane of ciliated epithelial cells in wild-type FVB mice (arrows in A). The specificity of this labelling is indicated by its absence after preabsorption of the antiserum with its corresponding antigenic peptide (B) and the lack of labelling in OCT1/2^-/- mice (C). Neither of the two OCT2-antibodies used in this study showed specific labelling of mouse bronchi (D, E). The spotty labelling of epithelial cells observed with the OCT2-antibody raised against the human sequence (E) was also observed in OCT1/2^-/- mice (F), indicating that this signal is non-specific. Specific OCT3-immunolabelling, documented by its absence in the preabsorption control (inset in G), is observed primarily on the bronchial smooth muscle (sm) and, less intensely, on epithelial cells (G). OCT3-localization in smooth muscle cells is confirmed by double-labelling immunofluorescence with OCT3-antibody and a monoclonal antibody against α-smooth muscle actin (SMA) (G') yielding the yellow signal in the merged image (G'). Bar represents 10 μm in A-F and 20 μm in G-G".