Receptor-Mediated Endocytosis and Drug Absorption

It is often mentioned that when drugs are absorbed paracellularly, they are dragged by a local water flux through the tight junctions. In this context, it is interesting to mention the Pappenheimer hypothesis [169,175,176], which suggests that the absorption of solutes across 

FIGURE 1.12 Top an electron microscopy image of an epithelial tight junction. The position of the tight junction at the apical end of the lateral membrane is marked with an arrowhead, whereas the position of a desmosome is indicated with an asterisk. Bar = 200 nm. (From Matter, K. and Baida, M.S., Methods, 30, 228, 2003. With permission.) Bottom a schematic location of the tight junctions, intermediate junctions, and actin cytoskeleton in the epithelial cell. (From Ballard, S.T., Hunter, J.H., and Taylor, A.E., Ann. Rev. Nutr., 15, 35, 1995. With permission.) 

Loosening Agents of Tight Junctions and the Time Required for Each of Them to Deplete Transmural TER as Analyzed in Cell Cultures and Isolated Epithelial Tissues 

Tight Junction Modulator Approximate Time Required to Deplete TER 

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