Figure 1.

Synergistic effects of combination of β₂-adrenergic receptor agonists with muscarinic receptor antagonists in airway smooth muscle. (A) Typical results of the inhibitory effect of procaterol (10 nM) in the absence (upper side) and presence (lower side) of tiotropium (1 nM) against methacholine (MCh, 10 μM)-induced contraction; (B) Values of percent inhibition of tiotropium (1 nM), procaterol (10 nM), and the combination of these two agents; (C) Values of percent inhibition of tiotropium (1 nM), salbutamol (100 nM), and the combination of these two agents. BI: the values of percent inhibition predicted by the Bliss independence theory, **: p < 0.01.