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Uncoagulable blood and life-threatening bleeding can result from the action of some snake venom toxins on haemostatic components of blood and vessel walls. Although envenoming by Micropechis ikaheka primarily affects neurones and muscle cells causing post-synaptic neuromuscular blockade and rhabdomyolysis, disturbances of haemostasis also occur. Therefore, the present study explored the effects of M. ikaheka venom on platelets and endothelium, which are important components of the haemostatic mechanism. The venom inhibited platelet aggregation in response to ADP and collagen, and also delayed clotting dependent on platelet activation or endothelial cell tissue factor expression. Some of these effects were reduced by the incubation of venom with a phospholipase A2 (PLA2) inhibitor and could be reproduced by a 17 kDa venom fraction containing a PLA2. In addition, an 11 kDa fraction containing a long-chain neurotoxin reduced ADP-induced aggregation. The venom was also found to reduce endothelial cell adherence to vitronectin-, fibronectin- and collagen-coated surfaces. These results suggest that, by inhibiting procoagulant activities of platelets and endothelial cells, a 17 kDa PLA2 plays an important role in the anticoagulant action of M. ikaheka venom.

Type

Journal article

Journal

Br J Haematol

Publication Date

09/2001

Volume

114

Pages

852 - 860

Keywords

Anticoagulants, Aristolochic Acids, Bleeding Time, Blood Coagulation, Cell Adhesion, Cells, Cultured, Collagen, Dose-Response Relationship, Drug, Elapid Venoms, Electrophoresis, Gel, Two-Dimensional, Endothelium, Vascular, Fibronectins, Humans, Mass Spectrometry, Phenanthrenes, Phospholipases A, Phospholipases A2, Platelet Aggregation, Proteins, Thromboplastin, Vitronectin