Rp-8-pCPT-Cyclic GMPS is a stable, cell-permeable cGMP analog that competitively inhibits cGMP-dependent protein kinases (cGKs), including cGK Iα and cGK II (IC50s = 18.3 and 0.16 μM, respectively). The pCPT (p-chlorophenylthio) group at the 8-position of the purine increases both enzyme affinity and membrane permeability over related compounds. At 10 μM, it blocks the relaxation of rat tail arteries induced by the nitric oxide donor SIN-1 .
