TY - JOUR T1 - Pharmacological characterization of the mechanism of action leading to synergism between glycopyrronium bromide and indacaterol fumarate JF - European Respiratory Journal JO - Eur Respir J DO - 10.1183/13993003.congress-2016.PA5057 VL - 48 IS - suppl 60 SP - PA5057 AU - Luigino Calzetta AU - Paola Rogliani AU - Ermanno Puxeddu AU - Josuel Ora AU - Francesco Facciolo AU - Maria Gabriella Matera AU - Mario Cazzola Y1 - 2016/09/01 UR - http://erj.ersjournals.com/content/48/suppl_60/PA5057.abstract N2 - Background Nowadays there is a considerable gap in knowledge concerning the mechanism(s) by which long-acting β2 agonists (LABAs) and long-acting muscarinic antagonists (LAMAs) interact to induce bronchodilation.Aim This study aimed to identify the mechanism(s) causing the synergistic interaction between the LAMA glycopyrronium bromide (GLY) and the LABA indacaterol fumarate (IND) in human bronchial tissue.Methods The influence of GLY plus IND was assessed on the release of acetylcholine (ACh) and concentrations of cAMP in human isolated airways. Iberiotoxin (IbTX, 100 nM) was used to block the KCa++ channels, tetanus toxin (TeTX, 10 nM) to inhibit the synaptic vesicle exocytosis of ACh, and quinine (100 μM) to reduce the release of non-neurogenic ACh.Results The co-administration of GLY and IND reduced the release of ACh from epithelial cells (-36.6±4.7%, P<0.01 vs. control) but not from bronchi, and enhanced cAMP levels in both bronchi (+479.4±62.4%, P<0.01 vs. control) and epithelial cells (+29.1±7.1, P<0.05 vs. control), an effect that was inhibited by IbTX. TeTX inhibited the release of parasympathetic ACh (−60.0%±1.2%, P<0.001 vs. control), and both GLY and IND further enhanced this effect (−68.4%±1.8%, P<0.001 vs. control). Quinine did not influence (P>0.05) the effectiveness of GLY/IND combination in reducing the non-neurogenic release of ACh.Conclusions GLY/IND co-administration leads to a synergistic improvement of bronchodilation by increasing cAMP concentrations in both airway smooth muscle and bronchial epithelium and by decreasing ACh release from the epithelium. ER -