Effect of vasoconstrictor pre-treatment on obstruction, secretion and sneezing after nasal challenge with threshold and suprathreshold allergen doses.

Acute nasal allergen challenge produces airway obstruction which varies in amount and timing with the allergen dose delivered. To see whether different mechanisms might contribute variably to mucosal swelling with different amounts of allergen, we challenged sensitive volunteers with threshold and 10-times threshold allergen doses, with and without topical vasoconstrictor pre-treatment. The vasoconstrictor effectively eliminated obstruction at both allergen dose levels, suggesting that acute vascular changes were responsible for all the measurable obstruction seen with acute allergen provocation. Alpha-adrenergic vasoconstrictor pre-treatment was associated with increased weight of secretion and numbers of sneezes.