Under short-circuit conditions, vasoactive intestinal peptides (VIP) did not alter net Na+ movement but selectively stimulated net Cl- secretion across dog tracheal epithelium with a high affinity (K(m) ≃ 10-8 M). The increase in Cl- secretion was not different from the rise in short-circuit current (I(sc)). However, stimulation of Cl- secretion was not maximal, because the addition of isoproterenol (10-6 M) to VIP-treated tissues further increased the I(sc) by 54%. The effect of exogenous VIP was not blocked by a combination of atropine, phentolamine, propranolol (10-5 or 10-6 M) or tetrodotoxin (10-6 M). Under open-circuit conditions, VIP caused an increase in the net secretion of Cl- and Na+, but the changes did not reach statistical significance. We conclude that VIP acts directly on receptors on the surface of epithelial cells to stimulate active Cl- secretion. The abundance of VIP nerves in the submucosa suggests that VIP may be important in regulation of fluid movement across the epithelium.
|Original language||English (US)|
|Number of pages||5|
|Journal||Journal of Applied Physiology Respiratory Environmental and Exercise Physiology|
|State||Published - 1983|
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