TACHYKININS INCREASE VASCULAR-PERMEABILITY IN THE GASTROINTESTINAL-TRACT OF THE RAT

The occurrence of inflammation as indicated by extravasation of Evans blue bound to plasma proteins was examined in various parts of the gas trointestinal tract in the rat following administration of tachykinins , capsaicin and hydrochloric acid. intravenous neurokinin A dose-depen dently induced extravasation in stomach, duodenum. jejunum, caecum and colon. but had no effect in ileum. Neurokinin B equipotently induced extravasation in the stomach but had no effect in other parts of the g ut and substance P had no effects on extravasation of Evans blue in an y of the examined parts of the gastrointestinal tract. Capsaicin given intraperitoneally increased vascular permeability in stomach and duod enum only. while extravasation of Evans blue alter capsaicin given int raluminally did not differ from the effect of the vehicle alone. As a comparison. HCl given intraluminally in the duodenum was found to indu ce a prominent extravasation of Evans blue of a greater magnitude than that of tachykinins. We suggest that tachykinins. and in particular n eurokinin A, may be of importance for extravasation of plasma proteins as part oi inflammatory reactions in the upper and lower gastrointest inal tract.