title: Platelet alpha-granule secretion and its modification by SC-57101A, a GPIIb/IIIa antagonist.
abstract: Platelet-agonist interaction results in aggregatory and secretory responses. While the activation of glycoprotein (GP) IIb/IIIa plays an essential role in platelet aggregation, its role in granule secretion is not clear. The present study was performed to examine the effect of 3-[[[[1-[4-(aminoiminomethyl) phenyl]-2-oxo-3S-pyrrolidinyl]amino]carbonyl]amino]-propanoate monohydrochloride salt (SC-57101A), a GPIIb/IIIa antagonist, on platelet alpha-granule secretion responses to collagen, ADP, and thrombin receptor activating peptide (TRAP). Both SC-57101A and prostaglandin E(1) (PGE(1)) inhibited collagen-, ADP-, and TRAP-induced platelet aggregation in a concentration-dependent manner. SC-57101A inhibited the collagen- and ADP-induced release of platelet-derived growth factor (PDGF) and beta-thromboglobulin (beta-TG) from platelets, but not TRAP-induced secretion of these granule contents. On the other hand, PGE(1) inhibited the release of PDGF and beta-TG from platelets activated with all the agonists used. ADP and TRAP elicited P-selectin expression in the absence of platelet aggregation, while collagen produced no such reaction. SC-57101A only moderately inhibited P-selectin expression induced by ADP and had no inhibitory effect on that induced by TRAP. The inhibition of ADP-induced secretion of alpha-granule contents by SC-57101A was abolished when platelets were pretreated with aspirin. These results suggest that GPIIb/IIIa activation plays a minor role, if any, in alpha-granule secretion in human platelets.
authors.affiliation: Pharmacology and Molecular Biology Research Laboratories, Sankyo Co., Ltd., 1-2-58 Hiromachi, Shinagawa-ku, Tokyo 140-8710, Japan. togawa@shina.sankyo.co.jp
authors.forename: Taketoshi
authors.initials: T
authors.lastname: Ogawa
authors.forename: Atsuhiro
authors.initials: A
authors.lastname: Sugidachi
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Otsuguro
authors.forename: Takashi
authors.initials: T
authors.lastname: Isobe
authors.forename: Fumitoshi
authors.initials: F
authors.lastname: Asai
mesh_terms: D001241:Aspirin / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D004347:Drug Interactions; D054641:Dual Specificity Phosphatase 2; D006801:Humans; D066298:In Vitro Techniques; D019007:P-Selectin / Q000096:biosynthesis / Q000378:metabolism*; D010974:Platelet Aggregation; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000037:antagonists & inhibitors*; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D054648:Protein Phosphatase 2; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D014508:Urea / Q000031:analogs & derivatives / Q000494:pharmacology*; D015091:beta-Alanine / Q000031:analogs & derivatives / Q000494:pharmacology*; D001620:beta-Thromboglobulin / Q000378:metabolism
chemical_list: D019007:P-Selectin; D010975:Platelet Aggregation Inhibitors; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D010982:Platelet-Derived Growth Factor; C406709:SC 57101B; D001620:beta-Thromboglobulin; D015091:beta-Alanine; D014508:Urea; D054648:Protein Phosphatase 2; C517032:DUSP2 protein, human; D054641:Dual Specificity Phosphatase 2; D017027:Protein Tyrosine Phosphatases; D001241:Aspirin