Rp-cAMPS triethylammonium salt is an analog of cAMP which acts as a potent, competitive and cell-permeable antagonist of cAMP-induced activation of cAMP-dependent PKA I and II (K_is of 6.05 µM and 9.75 µM, respectively). Rp-cAMPS triethylammonium salt is resistant to hydrolysis by phosphodiesterases^{[1][2][3][4][5]}. IC50 & Target: Ki: 6.05 µM (PKA I) and 9.75 µM (PKA II)^[1] In Vitro: A membrane-permeable competitive cAMP antagonist (Rp-cAMPS) that blocks PKA activation by binding to the regulatory subunits without dissociating the kinase holoenzyme also inhibits synaptic plasticity but has no effect on normal synaptic transmission^[1]. In Vivo: Rp-cAMPS (10 μM, 15 min) decreases the monosynaptic EPSCs evoked at the PB-CeLC and BLA-CeLC synapses in slices from arthritic rats but not in control neurons from normal animals. The inhibitory effect of Rp-cAMPS is significant compared to predrug (ACSF) control values obtained in the same neurons^[1].