Figure 3.

Airway smooth muscle contractions to G_αq-coupled receptor agonists are impaired in βAR^–/– tracheal rings. The contractile responses to the M₃R agonist acetylcholine (ACh) (10 nM−1.0 mM) and the TXA₂R agonist U46619 (1.0 nM–0.1 mM) were ascertained in tracheal rings from βAR^–/– mice and wild-type littermates. Shown is the maximal absolute isometric force evoked by the indicated agents. Maximal responses to acetylcholine and U46619 were depressed in the βAR^–/– mice, while the contractile responses to the cell-permeabilizing agent β-escin (500 μM) were preserved. Results are from five to seven experiments. *P = 0.005; ⁺P = 0.024.