title: Antiplatelet effects of KW-7, a new inhibitor of cyclic nucleotide phosphodiesterases.
abstract: The antiplatelet effect of a new synthetic compound, 8,9-dimethoxyl-1-(4-methoxy-phenyl)-5,6-dihydro-pyrrolo[2,1-a]isoquinoline-2,3-dione (KW-7), was determined in rabbit platelets. KW-7 concentration-dependently prevented platelet aggregation caused by arachidonic acid, collagen, platelet-activating factor, and thrombin. KW-7 induced a substantial increase in cyclic AMP levels and a smaller increase in cyclic GMP levels in platelets. In platelet homogenates, KW-7 inhibited both cyclic AMP- and cyclic GMP-phosphodiesterase activities. The antiplatelet effect of KW-7 was reversed by SQ22536 (an inhibitor of adenylate cyclase) and H89 (an inhibitor of protein kinase A) but not by ODQ (an inhibitor of soluble guanylate cyclase). These data suggest that the antiplatelet effect of KW-7 is cyclic AMP-dependent, and is through inhibition of platelet phosphodiesterases. In addition, KW-7 inhibited arachidonic acid-stimulated thromboxane production; this effect was associated with an increase in prostaglandin D(2) levels indicating KW-7 is also an inhibitor of thromboxane synthase. The dual inhibition of KW-7 on phosphodiesterase and thromboxane synthase might provide an attractive target in developing antiplatelet drugs.
authors.affiliation: Graduate Institute of Natural Products, Kaohsiung Medical University, 100 Shih Chuan 1st Road, Kaohsiung 807, Taiwan. ccwu@kmu.edu.tw
authors.forename: Chin-Chung
authors.initials: CC
authors.lastname: Wu
authors.forename: Wei-Ya
authors.initials: WY
authors.lastname: Wang
authors.forename: Reen-Yen
authors.initials: RY
authors.lastname: Kuo
authors.forename: Fang-Rong
authors.initials: FR
authors.lastname: Chang
authors.forename: Yang-Chang
authors.initials: YC
authors.lastname: Wu
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000818:Animals; D001792:Blood Platelets / Q000187:drug effects / Q000201:enzymology; D004305:Dose-Response Relationship, Drug; D007546:Isoquinolines / Q000737:chemistry / Q000494:pharmacology*; D010726:Phosphodiesterase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D010975:Platelet Aggregation Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D011817:Rabbits; D012756:Sheep
chemical_list: D007546:Isoquinolines; D010726:Phosphodiesterase Inhibitors; D010975:Platelet Aggregation Inhibitors; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D015106:3',5'-Cyclic-GMP Phosphodiesterases