Tachykinins may mediate capsaicin-induced, but not vagally induced motility in porcine antrum.

Tachykinins are thought to be involved in extrinsic control of motility in the gastrointestinal tract. Using the isolated perfused porcine antrum with intact vagal innervation, we studied the effects of substance P, neurokinin A and capsaicin infusion, and electrical stimulation of the vagus nerves on antral motility without or with infusion of non-peptide antagonists for NK-1 receptors (CP96345) and NK-2 receptors (SR48968). Substance P and neurokinin A stimulated antral motility in a dose-dependent manner. The effect could be inhibited by atropine or a combination of the NK-1 and NK-2 receptor antagonists. Electrical stimulation of the vagus nerves and infusion of capsaicin (10(-5) M) stimulated antral motility. Vagally induced motility was not influenced by infusion of CP96345 and SR48968, whereas the effect of capsaicin was blocked. We conclude that tachykinins may be involved in regulation of antral motility through sensory nerves in the porcine antrum, but they do not seem to be involved in vagal regulation of antral motility.