As ions move across epithelial sheets, they can do so either through the cells (transcellular) or between them (paracellular). Such transfers result in the development of trans-epithelial potential differences (P.D.’s) that are readily observed when these epithelia are set up in Ussing chambers, in vitro . Alterations in the P.D.’s thus developed can be conveniently analyzed in terms of the modulation of either one or both of the above routes of permeation. Although a number of transmitters and hormones have been shown to modulate trans cellular ion movements, relatively few modulators of paracellular pathways have been described; these include, among others, cyclic AMP, Ca 2+, carbachol, pancreozymins, and prostaglandins [2–5]. Luminal addition of several peptides [6–9] produce marked effects on the isolated canine tracheal epithelium. Our studies reported here suggest that these pep tides (SP, tachykinins, bradykinin) could rapidly alter the conductance of the paracellular pathways.
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- Peptides as Promotors of Paracellular Permeability: A Novel Role For Tachykinins?
P. K. Rangachari
- Springer New York
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