THE ACTIVATION OF THE BLOOD CLOTTING CASCADE BY Tityus discrepans VENOM AND ITS ROLE IN THE GENESIS OF ACUTE LUNG EDEMA.
G. DSuze
, C. Sevcik, R. Apitz-Castro
, A. Comellas
, R. Sanchez-De-León
Laboratorio de Neurofarmacología Celular, Laboratorio de Trombosis Experimental, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas (IVIC), Apartado 21827, Caracas 1020A, D.F. Venezuela. Unidad de Fisiología Respiratoria, Instituto de Medicina Experimental (IME), Universidad Central de Venezuela, Caracas, D. F.
The crude venom of Tityus discrepans (560µg/ml) induces the clotting of human plasma in the presence of 50 µM Ca
at 37°C, stimulating the clotting cascade in approximately 1 minute. The pre-coagulant activity is inhibited in the absence of calcium indicating that the venom requires this ion to act. TITYUS discrepans venom does not seem to act as a platelet aggregator nor directly on fibrinogen. The clotting effect of T discrepans venom on the development of lung edema was studied. Three groups of rabbits were exposed to the venom (1mg/kg). Two groups were pretreated as follows: one group with heparin, an anticoagulant, (5000 U every 12h), the other with ajoene, anti-platelet, (15mg/kg). The animals that received venom only as well as those pretreated with ajoene developed severe edema with an intra-alveolar hyaline membrane, abundant microthrombs, thickening of intra-alveolar septa, and marked intra-bronchial, intra-vascular and intra-alveolar lymphocytosis. In contrast, the animals pretreated with heparin did not develop lung edema. Ajoene is an organic molecule, which prevents platelet aggregation. Therefore, our results with heparin and ajoene support the idea that lung edema caused by Tityus venom occurs as a result of an indirect mechanism that may involve the activation of clotting factors.
This work has been partially financed by CONICIT, Project S1-95000722.
Publication Dates
-
Publication in this collection
16 Apr 1999 -
Date of issue
1999
