Effect of dextran and induced thrombocytopenia on the lysability of ex vivo thrombi in dogs.

The lysability of thrombi and clots was studied in intact and thrombocytopenic dogs. The thrombi were formed in ex vivo in rotating. Chandler loops, the clots were formed in plastic tubes. Infustion of dextran 70 to the intact dogs was followed by a significant increase in the lysability of the thrombi but not of the clots. Thrombocytopenia caused an increase in the lysability of both thrombi and clots. After infusion of dextran to thrombocytopenic dogs a further increase was noted in the lysability of thrombi but not of clots. The results indicate that dextran and induced thrombocytopenia increase the lysability of thrombi by different mechanisms. The different behaviour between thrombi and clots is probably due to the difference in structure between them particularly with regard to the distribution of platelets. It is suggested that dextran decreased the thrombus statility by impairing the platelet surface function.