Ki: 170 nM (PDE V)

Win 58237 is a competitive inhibitor of cGMP PDE V from canine aorta, with a K _i value of 170 nM. Win 58237 is a potent inhibitor of PDE V isolated from vascular tissue with an IC ₅₀ value of 240 nM. It is a relatively less potent inhibitor of calmodulin-sensitive PDE I and cGMP-inhibitable cyclic AMP PDE III; but does inhibit cyclic AMP PDE IV with an IC ₅₀ value of approximately 300 nM. Win 58237 possesses vasorelaxant activity in the presence of an intact endothelium or nitric oxide.

Win 58237 (0.3-3.0 mg/kg i.v.) decreases mean arterial pressure in conscious spontaneously hypertensive rats with an associated increase in vascular (aortic) cGMP content in vivo. Win 58237 (10 mg/kg i.v.) increases plasma cGMP levels, from basal levels of 6.7 ± 1.0 to 31.4 ± 3.5 fmol/μL.