EFFECTS OF AMBLYOMIN-X IN THE CLASSIC COAGULATION ASSAYS

VENTURA J.S., BATISTA I.F.C., CHUDZINSKI-TAVASSI A.M.

Biochemistry and Biophysics Laboratory, Butantan Institute, Avenue Vital Brazil, 1500, Butantã, 05503-900 São Paulo/SP, Brazil.

In the bloodsuckers saliva there are several compounds whose interfere on the physiological systems of their hosts such as coagulation, platelet aggregation and fibrinolysis. Focusing the blood clotting system a recombinant protein named Amblyomin-X was cloned and expressed, this protein is able to inhibit the Factor Xa activity and its effects were compared to the effects caused by Heparin which is a classical anticoagulant “in vivo” and “in vitro”. To perform the “in vivo” experiments normal mice were injected with Amblyomin-X (1 and 2 mg/kg body weight, iv), Heparin (1 and 2 mg/kg body weight, iv) or saline (control), blood was collected 5 and 24 h after the injection and the prothrombin time (PT) and activated partial thromboplastin time (APTT) were assayed. To the “in vitro” experiments a pool of normal mice plasma was obtained and incubated with the anticoagulants (Amblyomin-X 0.02 ug/ul to 1.0 ug/ul and Heparin 0.02 ug/ul to 0.2 ug/ul) or saline as control. The obtained data to the “in vivo” experiment showed that the PT is not affected neither by Amblyomin-X nor by Heparin. On the other hand APTT is prolonged to the both proteins. To the “in vitro” experiments the PT is not affected by Amblyomin-X, however in presence of Heparin a greater PT prolongation is observed. The APTT is prolonged to the both proteins. The anticoagulant action of Heparin was more evident than Amblyomin-X. Heparin catalyzes the antithrombin inhibition and Ambliomin-X acts directly on FXa inhibition.

SUPPORTED BY FAPESP and FINEP/COINFAR

CORRESPONDENCE TO: jsventura@butantan.gov.br