NK-1 receptors mediate the tachykinin stimulation of salivary secretion: selective agonists provide further evidence.

The relative contribution of NK-1, NK-2 and NK-3 receptors to the sialogogic response to i.v. tachykinins was investigated in urethane-anesthetized rats. [Pro9,Met(O2)11]substance P (SP), a selective NK-1 receptor agonist, was about 10 times more potent than SP itself and its action was unaffected by atropine pretreatment. On the other hand [Nle10]neurokinin A (NKA)-(4-10) and [MePhe7]neurokinin B (NKB), two selective agonists for NK-2 and NK-3 receptors, respectively, were ineffective.