Evidence for the involvement of substance P in the atropine-resistant peristalsis of the guinea-pig ileum.

In the isolated, vascularly perfused guinea-pig ileum, peristalsis could be induced by raising the intraluminal pressure in the presence of atropine. Atropine-resistant peristalsis was greatly inhibited or abolished by the substance P antagonist (D-Pro2, D-Trp7.9)-substance P, substance P desensitization, hexamethonium and by the enkephalin analogue FK 33-824. It is concluded that substance P neurones of the intestine play an important role in the atropine-resistant peristalsis of the guinea-pig ileum.