Nasal Nitric Oxide Does Not Control Basal Nasal Patency or Acute Congestion following Allergen Challenge in Allergic Rhinitis

Nasal nitric oxide (NO), a powerful vasodilator, could control the filling of nasal capacitance vessels, thus determining nasal patency and mediating the acute congestion accompanying allergen challenge. We examined the effect of topical N-nitro-L-arginine-methyl-ester (L-NAME; 100 to 200 mg), an NO synthase inhibitor, on nasal NO and on nasal patency assessed by acoustic rhinometry in 7 subjects with nasal allergy, and in 4 subjects we examined the effects of nasal allergen challenge on nasal NO before and after a short course of nasal steroid. After L-NAME, nasal NO fell to 42.1%+/-15.7% of baseline (p < .0001) with no significant change in minimal cross-sectional area. After allergen challenge, acute congestion was associated with a significant fall in nasal NO, which returned to baseline by 4 hours, when the congestion resolved. Repeat challenge after 2 weeks of nasal corticosteroid yielded similar findings. A role for NO in modulating vascular tone was not supported by the present study.