Figure 3.

Activation of β₂AR induces Ca²⁺ mobilization by 2 pathways: directly by Gβγ subunits and indirectly by Gα_s-AC-cAMP-PKA/Epac pathway. A, B) Formoterol (1 nM)-induced Ca²⁺ mobilization was lost after inhibition of Gα_s (10 μM NF449) or Gβγ subunits (50 μM gallein), but not Gα_i/o (10 μM NF023) (n = 3–6). C–F) Inhibition of AC (100 μM ddA) (C, D) and PKA or Epac (1 μM KT5720 or 50 μM ESI-09, respectively) (E, F) abolished Ca²⁺ responses to 1 nM formoterol (n = 3–9). Bars represent means, error bars sem. ***P < 0.001, 2-way ANOVA with Dunnett’s (B, F) or Sidak’s (D) multiple comparison test.