Figure 5.

PE-induced inhibition of constitutive endocytosis revealed by Alexa 488 hydrazide. Mucosal explants cultured for 1 h in the absence (A-C) or presence (E-F) of 2 mM DG and in the presence of 10 µg/ml of the fluorescent polar tracer Alexa 488 hydrazide (green color in A, D). Sections were immunolabeled for aminopeptidase N (red color in A, D), Na⁺/K⁺-ATPase (red color in B, E), or with Alexa 488-conjugated phalloidin (green color in C, F). All images shown were captured at pairwise identical settings of the microscope. A: The fluorescent polar tracer Alexa 488 hydrazide is taken up into distinct subapical punctae like LY (Fig. 4), but is not visible in the paracellular space and only weakly stains the lamina propria. D: No Alexa 488 hydrazide accumulated in subapical punctae, and diffuse cytoplasmic staining of the enterocytes was moderate in comparison with LY (Fig. 4). Neither the brush border marker aminopeptidase N, the basolateral marker Na⁺/K⁺-ATPase, nor the cortical cytoskeleton marker phalloidin were visibly affected by DG. The images shown of each situation are representative of at least 5 images. Bars: 20 µm.