Rp-8-CPT-cAMPS is a powerful and competitive antagonist of cAMP-induced activation of cAMP-dependent protein kinase (PKA) I and II. Acting as a potent cAMP analog, Rp-8-CPT-cAMPS exhibits a preference for site A of RI over site A of RII. Additionally, it favors site B of RII over site B of RI. This compound effectively inhibits cAMP-dependent PKA activation and demonstrates selectivity in binding to specific sites within the protein kinase.

Rp-8-CPT-cAMPS, at a concentration of 100 μM for 15 minutes, inhibits the phosphorylation of VASP by 6-Bnz-cAMP and significantly reduces VASP phosphorylation caused by forskolin and fenoterol. At the same concentration but extended to 30 minutes, it decreases GTP-loading of Rap1 triggered by both 8-pCPT-2'-O-Me-cAMP and 6-Bnz-cAMP. Additionally, it substantially lowers the increase in bradykinin-induced IL-8 release facilitated by PKA activator 6-Bnz-cAMP and Epac activator 8-pCPT-2'-O-Me-cAMP. At a lower concentration of 10 μM, Rp-8-CPT-cAMPS hinders both endothelium-dependent and -independent relaxation caused by venom in pre-contracted rat mesenteric artery rings.