Role of nitric oxide and superoxide in allergen‐induced airway hyperreactivity after the late asthmatic reaction in guinea‐pigs

In the present study, the roles of nitric oxide (NO) and superoxide anions (O2−) in allergen‐induced airway hyperreactivity (AHR) after the late asthmatic reaction (LAR) were investigated ex vivo, by examining the effects of the NO synthase inhibitor Nω‐nitro‐L‐arginine methyl ester (L‐NAME) and superoxide dismutase (SOD) on the responsiveness to methacholine of isolated perfused guinea‐pig treacheae from unchallenged (control) animals and from animals 24 h after ovalbumin challenge. At 24 h after allergen challenge, the animals developed AHR in vivo, as indicated by a mean 2.63±0.54 fold (P