Inhibition of neurogenic plasma exudation in guinea‐pig airways by CP‐96,345, a new non‐peptide NK₁ receptor antagonist

A new non‐peptide tachykinin antagonist, CP‐96,345, inhibited airway plasma exudation induced in guinea‐pigs by i.v. substance P in a dose‐dependent manner with dose‐ratios in the main bronchi of 5 at 1 nmol kg −1 and 19 at 100 nmol kg −1 . At 100 nmol kg −1 , CP‐96,345 completely inhibited plasma exudation induced by either electrical stimulation of the cervical vagus nerves or i.v. capsaicin, indicating inhibition of the effects of endogenous tachykinins, but did not inhibit the bronchoconstrictor response to neurokinin A, suggesting selectivity for NK 1 receptors. CP‐96,345 may be useful in examining the role of endogenous tachykinins in vivo .