title: Antiplatelet activity of [5-(2-methoxy-5-chlorophenyl)furan-2-ylcarbonyl]guanidine (KR-32570), a novel sodium/hydrogen exchanger-1 and its mechanism of action.
abstract: The antiplatelet effects of a novel guanidine derivative, KR-32570 ([5-(2-methoxy-5-chlorophenyl) furan-2-ylcarbonyl]guanidine), were investigated with an emphasis on the mechanisms underlying its inhibition of collagen-induced platelet aggregation. KR-32570 significantly inhibited the aggregation of washed rabbit platelets induced by collagen (10 microg/mL), thrombin (0.05 U/mL), arachidonic acid (100 microM), a thromboxane (TX) A2 mimetic agent U46619 (9,11-dideoxy-9,11-methanoepoxy-prostaglandin F2, 1 microM) and a Ca2+ ATPase inhibitor thapsigargin (0.5 microM) (IC50 values: 13.8 +/- 1.8, 26.3 +/- 1.2, 8.5 +/- 0.9, 4.3 +/- 1.7 and 49.8 +/- 1.4 microM, respectively). KR-32570 inhibited the collagen-induced liberation of [3H]arachidonic acid from the platelets in a concentration dependent manner with complete inhibition being observed at 50 microM. The TXA2 synthase assay showed that KR-32570 also inhibited the conversion of the substrate PGH2 to TXB2 at all concentrations. Furthermore, KR-32570 significantly inhibited the [Ca2+]i mobilization induced by collagen at 50 microM, which is the concentration that completely inhibits platelet aggregation. KR-32570 also decreased the level of collagen (10 microg/mL)-induced secretion of serotonin from the dense-granule contents of platelets, and inhibited the NHE-1-mediated rabbit platelet swelling induced by intracellular acidification. These results suggest that the antiplatelet activity of KR-32570 against collagen-induced platelet aggregation is mediated mainly by inhibiting the release of arachidonic acid, TXA2 synthase, the mobilization of cytosolic Ca2+ and NHE-1.
authors.affiliation: College of Pharmacy, Chungbuk National University, Cheongju 361-763, Korea.
authors.forename: Kyung-Sup
authors.initials: KS
authors.lastname: Lee
authors.forename: Jung-Woo
authors.initials: JW
authors.lastname: Park
authors.forename: Yong-Ri
authors.initials: YR
authors.lastname: Jin
authors.forename: In-Sang
authors.initials: IS
authors.lastname: Jung
authors.forename: Mi-Ra
authors.initials: MR
authors.lastname: Cho
authors.forename: Kyu-Yang
authors.initials: KY
authors.lastname: Yi
authors.forename: Sung-Eun
authors.initials: SE
authors.lastname: Yoo
authors.forename: Hun-Jong
authors.initials: HJ
authors.lastname: Chung
authors.forename: Yeo-Pyo
authors.initials: YP
authors.lastname: Yun
authors.forename: Tae-Kyu
authors.initials: TK
authors.lastname: Park
authors.forename: Hwa-Sup
authors.initials: HS
authors.lastname: Shin
mesh_terms: D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D003094:Collagen; D004305:Dose-Response Relationship, Drug; D006146:Guanidines / Q000494:pharmacology*; D066298:In Vitro Techniques; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D011817:Rabbits; D012701:Serotonin / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013929:Thromboxane B2 / Q000378:metabolism; D013930:Thromboxane-A Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D006146:Guanidines; D010975:Platelet Aggregation Inhibitors; D017923:Sodium-Hydrogen Exchangers; C069139:growth factor-activatable Na-H exchanger NHE-1; D016718:Arachidonic Acid; C502305:(5-(2-methoxy-5-chloro-5-phenyl)furan-2-ylcarbonyl)guanidine; D012701:Serotonin; D013929:Thromboxane B2; D003094:Collagen; D013930:Thromboxane-A Synthase; D002118:Calcium