Effects of FR 113680 and FK 224, novel tachykinin receptor antagonists, on cigarette smoke-induced rat tracheal plasma extravasation.

We examined the effects of novel tachykinin antagonists, FR 113680 (N alpha-[N alpha-(N alpha-acetyl-L-threonyl)-N1-formyl-D-tryptophyl]-N- methyl-N-phenylmethyl-L-phenylalaninamide) and FK 224 (N-[N2-[N-[N-[N-[2,3-didehydro-N-methyl-N-[N[3-(2-phenthylpheny l) - propionyl]-L-threonyl]-tyrosyl]-L-leucynyl]-D-phenylalanyl]-L-allo - threonyl]-L-asparaginyl]-L-serine nu-lactone) on rat tracheal plasma extravasation induced by cigarette smoke. Intravenous injection of FK 224 (0.032-3.2 mg kg-1) inhibited rat tracheal plasma extravasation induced by cigarette smoke and capsaicin. FR 113680 (32 mg kg-1 i.v.) also significantly inhibited cigarette smoke-induced plasma extravasation, whereas D-chlorpheniramine maleate, FPL 55712, atropine sulfate and indomethacin had no effect. Tracheal plasma extravasation induced by substance P (SP) and neurokinin A (NKA), but not histamine, was also reduced by intravenous administration of FR 113680 and FK 224. These findings suggest that cigarette smoke stimulates primary afferent sensory nerves, releases tachykinins and evokes plasma extravasation in rat trachea.