Although the apelin (AP) and its specific receptor APJ are highly expressed in the lung, biological functions of AP/APJ system are still under investigation. We studied the effects of AP on bronchial reactivity to acetylcholine (ACh) and terbutaline induced by allergen sensitization and challenge. Experiments were performed on bronchial rings obtained from normal (NR) or ovalbumin sensitized rat (OSR). Because recent studies have demonstrated that involvement of nitric oxide (NO) on AP effects, the bronchial tone and the NO production were simultaneously assessed. On OSR, the 10 uM API 3 pretreatment reduced the Emax of ACh-induced bronhoconstriction with more than 20% and shifted to the left the terbutaline dose-response curve. AP 13 effects were totally prevented by inhibition of all NO synthases (NOS) with 0.1 mM N(G)-nitroL-arginine methyl ester and only reduced by 0.1 mM aminoguanidine (inhibitor of inducible NOS). The simultaneously monitoring of NO releasing from bronchial rings confirmed the NO involvement on AP 13 effects. These results suggest that AP could reduced airway hyperreactivity by increasing bronchial constitutive NOS activity and provides a very interesting target for developing suitable therapeutic approaches.

Keywords: 

bronchus, nitric oxide, peptid