Coagulant and anticoagulant activities of Bothrops lanceolatus (Fer de lance) venom

Bothrops lanceolatus venom contains caseinolytic, phospholipase, esterase a nd haemorrhagic activities. We have investigated the coagulant and anticoag ulant actions of B. lanceolatus venom on human citrated plasma and on purif ied plasma components. Although B. Innceolatus venom up to 50 mu g/ml was u nable to clot citrated plasma, at concentrations greater than or equal to 5 mu g/ml the venom dose-dependently clotted purified human fibrinogen, indi cating the presence of a thrombin-like enzyme. Human plasma (final concentr ation greater than or equal to 12.5%) dose-dependently inhibited the venom- induced fibrinogen clotting. This finding suggested that endogenous plasma protease inhibitors can affect the venom's action on fibrinogen. To investi gate this possibility, B. lanceolatus venom was incubated with different pl asma protease inhibitors and the activity on fibrinogen tested, alpha(2)-Ma croglobulin and alpha(1)-antitrypsin did not interfere with the coagulant a ctivity of the venom whereas the antithrombin-III/heparin complex partially inhibited this activity. A non-toxic, acidic phospholipase A(2) purified f rom B. lanceolatus venom prolonged the activated partial thromboplastin tim e in human plasma from 39.7+/-0.5 s (control with saline) to 60.2+/-0.9 s w ith 50 mu g of PLA(2) (p < 0.001), suggesting an anticoagulant activity ass ociated with this enzyme. This anticoagulant activity may account for some of the effects of the venom on blood coagulation. (C) 2000 Elsevier Science Ltd. All rights reserved.