Figure 5 – Activity of ISO and the G_s-biased agonists on HASM cell relaxation.

(A) Time course of HASM cell relaxation induced by 10 μM ISO, SALB, RAC, DOB, or HIG. Data are mean ± SEM from 3 different HASM cell lines: ISO (n=342), SALB (n=257), DOB (n=215), HIG (n=214), RAC (n=218) where n is the number of cells per condition. Agonist-induced relaxation at 300 s was analyzed by one-way ANOVA, followed by Dunnett’s multiple comparisons test (comparing all data to SALB). (B) Inhibition of 10 μM ISO, RAC, DOB, or HIG-induced HASM cell relaxation by the β₂AR-specific antagonist ICI-118551 (10 μM ICI treated) or the β-antagonist propranolol (10 μM PROP treated). Data are mean ± SEM (n for untreated, ICI-treated and PROP-treated, respectively: ISO (n=258, 162, 156), RAC (n=152, 178, 167), DOB (n=122, 161, 192), HIG (n=204, 128, 150). Agonist-induced relaxation at 300 s was analyzed by one-way ANOVA, followed by Dunnett’s multiple comparisons test (comparing ISO, RAC, DOB and HIG in the presence or absence of ICI or PROP). (C) HASM cell desensitization induced by pretreating cells with 10 μM ISO, SALB, RAC, DOB, or HIG for 0.5, 4 or 18 h, followed by relaxation induced by 10 μM ISO. Data are mean ± SEM from 0.5, 4 and 18 h pretreatments, respectively: untreated (n=380, 262, 254), ISO (n=338, 278, 107), SALB (n=211, 189, 251), RAC (n=355, 227, 323), DOB (n=331, 209, 252) and HIG (n=229, 224, 172). Agonist-induced relaxation at 300 s was analyzed by one-way ANOVA, followed by Dunnett’s multiple comparisons test (comparing RAC, DOB and HIG to either SALB or ISO). ***p < 0.001