Crotoxin induces aggregation of human washed platelets

Abstract

Crotoxin induces aggregation of human washed platelets. Toxicon 32, 217–225, 1994.—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 A 2 (PLA 2). In this study, we have evaluated the ability of crotoxin to induce aggregation in human washed platelets. Human washed platelet aggregation was monitored in a Payton aggregometer and thromboxane B 2 (TXB 2) release measured by direct radio-immunoassay (RIA). Crotoxin (15–50 μg/ml) produced dose-dependent and irreversible human washed platelet aggregation, which was inhibited by pre-incubation of the platelets with sodium nitroprusside (50–500 μM) or iloprost (8–80 nM). Crotoxin also induced TXB 2 release (207 ± 8 ng/ml, n = 6), and although indomethacin significantly reduced the release of TXB 2 (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.