Cigarette smoke was delivered to anesthetized, artificially ventilated, guinea pigs via a tracheal cannula. Inhalation of cigarette smoke increased Evans blue dye extravasation in the trachea in a dose-dependent manner (1 to 10 puffs). Plasma extravasation increased after exposure to 3 puffs of cigarette smoke and reached a maximum after 10 puffs. The plasma extravasation evoked by exposure to 5 puffs was reduced by 61% due to the N141 tachykinin receptor antagonist, CP-99, 994 (4 mg/kg,

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... and was not affected by the bradykinin B2 receptor antagonist, HOE140 (0.1 ;,¢mol/kg, 1' . v.). These findings indicate that cigarette smoke increased plasma extravasation and directly stimulated the C-fiber of sensory nerves.