Summary
On human plasma, the venom of Vipera aspis has both an immediate procoagulant effect and a late fibrinogenolytic and fibrinolytic activity. This procoagulant effect is shown in presence of calcium ions and is observed even in the absence of phospholipids. Factors V and X are the main substrates necessary for this action.
The venom progressively hydrolyses fibrinogen impairing clot formation. It has a fibrinolytic action in the absence of plasminogen.
On platelets, the venom of Vipera aspis inhibits the aggregation induced by ADP, collagen or small amounts of adrenalin. Platelet phospholipids are hydrolysed by the venom and the hydrolysis products are hemolytic. With venom, platelets lose part of their procoagulant properties. The clot formation of PRP is impaired in the presence of the venom as seen on thromboelastogram.
