Quazinone is a selective inhibitor of phosphodiesterase 3 (PDE3) with positive inotropic and vasodilating properties.1,2 It induces relaxation of precontracted isolated human cavernous smooth muscle (IC50 = 4.2 μM).1 Quazinone (10-300 μg/kg) increases myocardial contractile force in anesthetized open-chest dogs in a dose-dependent manner, as well as decreases systolic and diastolic blood pressure.2 It also inhibits DNA synthesis induced by the PDGF isoform PDGF-BB in bovine coronary artery smooth muscle cells in a concentration-dependent manner.3

|1. Taher, A., Meyer, M., Stief, C.G., et al. Cyclic nucleotide phosphodiesterase in human cavernous smooth muscle. World J. Urol. 15(1), 32-35 (1997).|2. Eigenmann, R., Gerold, M., and Holck, M. Cardiovascular profile of Ro 13-6438, a novel positive inotropic agent with vasodilating properties. J. Cardiovasc. Pharmacol. 6(3), 511-519 (1984).|3. Osinski, M.T., and Schr•r, K. Inhibition of platelet-derived growth factor-induced mitogenesis by phosphodiesterase 3 inhibitors: Role of protein kinase A in vascular smooth muscle cell mitogenesis. Biochem. Pharmacol. 60(3), 381-387 (2000).