FIGURE 6.

Effect of PKA inhibition on the ability of β-agonist to relax precontracted murine tracheal rings. Tracheal rings were isolated from C57BL6 mice and infected for 48 h with lentivirus encoding GFP or PKI-GFP. A, GFP images of control, GFP-, or PKI-GFP-infected murine tracheal rings. The control ring was maintained in culture for 48 h but not infected with virus. B, representative immunoblot for GFP expression in lysates from GFP- and PKI-GFP-infected murine tracheal rings. C, KCl-normalized contraction of rings stimulated with MCh (1 μm). D, tracheal rings were precontracted with MCh (1 μm), and then changes in contractile force were measured in response to treatment with increasing doses of ISO. *, p < 0.05; †, p < 0.0001 versus GFP (GFP, n = 9; PKI, n = 12).