title: Crotoxin induces aggregation of human washed platelets.
abstract: Crotoxin, the main toxic component isolated from the venom of the South American rattlesnake Crotalus durissus terrificus, is a reversible protein complex composed of a non-toxic non-enzymatic acidic polypeptide (crotapotin) and a toxic basic phospholipase A2 (PLA2). In this study, we have evaluated the ability of crotoxin to induced aggregation in human washed platelets. Human washed platelet aggregation was monitored in a Payton aggregometer and thromboxane B2 (TXB2) release measured by direct radioimmunoassay (RIA). Crotoxin (15-50 micrograms/ml) produced dose-dependent and irreversible human washed platelet aggregation, which was inhibited by pre-incubation of the platelets with sodium nitroprusside (50-500 microM) or iloprost (8-80 nM). Crotoxin also induced TXB2 release (207 +/- 8 ng/ml, n = 6), and although indomethacin significantly reduced the release of TXB2 (to 23.5 +/- 5 ng/ml, P < 0.001, n = 6), it did not inhibit crotoxin-induced aggregation. Our results clearly demonstrate that crotoxin induces human washed platelet aggregation and that this phenomenon is independent of the formation of pro-aggregatory arachidonic acid metabolites.
authors.affiliation: Department of Biochemistry, UNICAMP, Campinas, SP, Brazil.
authors.forename: E C
authors.initials: EC
authors.lastname: Landucci
authors.forename: A
authors.initials: A
authors.lastname: Condino-Neto
authors.forename: A C
authors.initials: AC
authors.lastname: Perez
authors.forename: S
authors.initials: S
authors.lastname: Hyslop
authors.forename: A P
authors.initials: AP
authors.lastname: Corrado
authors.forename: J C
authors.initials: JC
authors.lastname: Novello
authors.forename: S
authors.initials: S
authors.lastname: Marangoni
authors.forename: B
authors.initials: B
authors.lastname: Oliveira
authors.forename: E
authors.initials: E
authors.lastname: Antunes
authors.forename: G
authors.initials: G
authors.lastname: de Nucci
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003439:Crotoxin / Q000302:isolation & purification / Q000494:pharmacology*; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D010741:Phospholipases A / Q000494:pharmacology; D054467:Phospholipases A2; D010974:Platelet Aggregation / Q000187:drug effects*
chemical_list: D003439:Crotoxin; D010741:Phospholipases A; D054467:Phospholipases A2