Sp-cAMPS triethylamine, a cAMP analog, serves as a potent activator of cAMP-dependent PKA I and II and acts as a competitive inhibitor of phosphodiesterase (PDE3A) with a K i of 47.6 uM. Additionally, it binds the PDE10 GAF domain with an EC 50 of 40 uM (1) (2) (3).