Fig. 1

CPECs uptake tPA in vitro. A Photomicrographs show that both CPECs in culture (top panel) and CPECs in situ (lower panel) express the marker TTR (white) and tight junctions (Occludin, yellow), scale bar 30 µm. B–E Primary cultures of CPECs were exposed to 40 nM tPA⁵⁵⁵ for 5-60 min (B–C) or to tPA⁵⁵⁵ (20-400 nM) for 15 min (D–E). B, D Photomicrographs (representative of n = 4) show time- and dose-dependent accumulation of tPA⁵⁵⁵ (magenta) in cell monolayers. Higher magnifications suggest an accumulation in vesicles; scale bar 40 µm. C, E Electrophoresis (representative of n = 4) and corresponding quantifications of fluorescence (expressed as percentage of maximal uptake; mean ± SEM; n = 4) of protein extracts from monolayer of CPECs exposed to tPA⁵⁵⁵ (40 nM) for 5-60 min (B–C) or to 20-400 nM tPA⁵⁵⁵ for 15 min (D–E). * Significant difference (p < 0.05), $ significant difference versus control (p < 0.05)