Fig. 2.

Effects of Ca²⁺-mediated inhibition of AC. a Graphical notation used in CellDesigner to depict β-AR signaling molecules AC, cAMP, Ca²⁺, and PKA. Ca²⁺-mediated inhibition of AC was deleted from Cooper’s original model. b Computational oscillation loop of β-AR signaling molecules. cAMP, Ca²⁺, AC, and PKA did not form a negative feedback loop. The intracellular concentration of cAMP at baseline (0 min) was taken as 1 (arbitrary units)