Effects of drugs affecting the renin-angiotensin system on venous thrombosis in normotensive rats.

The aim of this study was to compare the potential antithrombotic action of captopril (angiotensin converting enzyme inhibitor) and losartan (a selective AT1 receptor antagonist) after their chronic administration in a model of venous thrombosis in rats. Captopril significantly reduced the incidence of venous thrombosis (67% vs 14%; p < 0.05) and both drugs markedly reduced the weight of thrombus. At the same time the platelet aggregation was reduced only in rats treated with losartan (100 +/- 7% vs 52 +/- 11%; p < 0.001). The mean blood pressure dropped only after losartan administration. We observed no changes in "transection" bleeding time after both drugs administration. In conclusion, captopril and losartan exerted an antithrombotic effect in venous thrombosis model in rats. The precise mechanism of this action should be established.