Vasodilatory activity and antihypertensive profile mediated by inhibition of phosphodiesterase type 1 induced by a novel sulfonamide compound

LASSBio-985 is a sulfonamide compound designed as a simplified structure of a nonselective phosphodiesterase type 4 (PDE-4) inhibitor that promotes vasodilatory activity in vitro. PDE are enzymes responsible for the hydrolysis of cyclic adenosine 3',5'- monophosphate and cyclic guanosine 3',5'-monophosphate. Five different isozymes of PDE are found in vascular smooth muscle (PDE1-PDE5). Aortic rings, with or without endothelium, from male normotensive and spontaneously hypertensive rats (SHR) were prepared for isometric tension recording. Blood pressure was measured in Wistar Kyoto (WKY) rats and SHR during intravenous infusion of LASSBio-985 (10 mg/kg/min) during 15 min. LASSBio-985 induced a concentration-dependent vasodilation in aortic rings from normotensive and SHR, which was almost completely inhibited in endothelium-denuded vessels. Vasodilatory activity was also reduced in endothelium-intact aortic rings that had been pretreated with N(ω)-nitro-L-arginine methyl ester hydrochloride (L-NAME), a nitric oxide synthase inhibitor and 1H-[1,2,4]oxadiazolod[4,3-a]quinoxalin-1-one (ODQ), a guanylate cyclase inhibitor. LASSBio-985-induced vasodilation was also inhibited by sildenafil (100 μm) and SQ 22536, a PDE5 inhibitor and adenylate cyclase inhibitor, respectively. To evaluate the involvement of some endothelial receptors, atropine, diphenhydramine, HOE 140, naloxone, propranolol, indomethacin, and wortmannin were tested, but none inhibited the effects of LASSBio-985. The residual effect observed on endothelium-denuded aortic rings was abolished by nicardipine, a voltage-sensitive-Ca(2+)-channel blocker. Intravenous infusion of LASSBio-985 (10 mg/kg/min) significantly reduced systolic and diastolic pressures in both WKY and SHR. LASSBio-985 is a compound with vasodilatory activity, which could be consequent to PDE1 inhibition and voltage-sensitive-Ca(2+)-channel blockade.