Fig. 1

a Relaxant effect of glycopyrronium and indacaterol in human isolated bronchi submaximally contracted (EC₇₀) with acetylcholine (a) and histamine (d). Expected and observed relaxant response induced by glycopyrronium and indacaterol in human isolated bronchi submaximally pre-contracted (EC₇₀) with acetylcholine (b) and histamine (e), as predicted by the Bliss Independence theory for the whole range of EC (% E_max). The isoeffective concentrations of glycopyrronium and indacaterol have been indicated below the X-axis. c Delta effect between observed and expected relaxant response induced by glycopyrronium and indacaterol in human isolated bronchi submaximally pre-contracted with acetylcholine (EC₇₀), as predicted by the Bliss Independence theory for the whole range of EC (% E_max). The isoeffective concentrations of glycopyrronium and indacaterol have been indicated below the X-axis. Data are expressed as mean ± SEM from experiments performed using samples from n = 3 different subjects. *P < 0.05, **P < 0.01 and ***P < 0.001 vs. expected relaxant response (statistical significance assessed by t test analysis). EC_n: dose inducing n% maximal effect; E_max: maximal effect; GLY: glycopyrronium bromide; IND: indacaterol fumarate