Effect of nitric oxide inhibition on nasal airway resistance after nasal allergen challenge in allergic rhinitis

Background Nitric oxide has been detected by chemiluminescence in the lumen of nasal airway, which is increased in nasal breathing in patients with se asonal rhinitis during a chronic exposure. The purpose of this study was to determinate the effect of a NO-synthase inhibitor (NL)-L-G-arginine methyl ester (L-NAME) on nasal airway resistance (NAR) in patients with seasonal allergic rhinitis after an acute challenge to the allergen. Methods Nitric oxide levels in the nose were measured by the chemiluminesce nce method in nine non-atopic volunteers and in seven patients with seasona l rhinitis at rest and after an acute challenge with the allergen. NAR were measured by active anterior rhinomanometry. Results Basal nasal NO concentration in allergic rhinitis was 496.5 +/- 151 .4 parts per billion (ppb). (n = 7) and it was not significantly different from levels found in the control group: 458.4 +/- 105.9 ppb (n = 9). The to pical administration of L-NAME in allergic rhinitis reduced the NO concentr ation (338.6 +/- 99.3 ppb, P < 0.001; n = 7). In the rhinitic patients the challenge with the allergen did not modify the nasal NO levels (504.5 <plus /minus> 138.5 ppb). The application of the allergen after the pretreatment with placebo caused a significant increase in NAR (from 0.32 +/- 0.11 Pa s cm(-3) to 1.01 +/- 0.12 Pa s cm(-3), P < 0.001; n = 7). Pre-treatment with L-NAME did not prevent the increase in NAR induced by allergen challenge (f rom 0.36 <plus/minus> 0.15 Pa s cm(-3) to 1.06 +/- 0.26 Pa s cm(-3)). Conclusions The results indicate that nasal administration of a NOS inhibit or L-NAME, at doses capable of decreasing nasal NO levels, has no effect on NAR and it does not prevent the NAR increase induced by an acute challenge with allergen in subjects with seasonal rhinitis.