Substance P and vasoactive intestinal peptide in serotonin-induced nasal secretions in normal subjects

The aim of this study was to examine if nasal secretions contained substance P and/or vasoactive intestinal peptide. Serotonin nasal challenge was performed in 14 normal subjects 15 min after intranasal pretreatment (double-blind) with atropine, methysergide, chlorpheniramine or isotonic saline. Serotonin induced a dose dependent increase in secretion (P < 0.05), and only pretreatment with atropine reduced the secretion (P < 0.02). Substance P, measured by radioimmunoassay, was found in all of the examined secretions (n= 100) with a median concentration of 13.7 pmol/1 (range 1.7–125.0). Serotonin challenge increased the concentration or content of substance P in a dose-related fashion (P < 0.01). The different pretreatments did not affect the concentration of substance P. Vasoactive intestinal peptide was found in low concentration in 37% of the secretions with a median concentration of 0 pmol/1 (range 0–50.0).