Effect of Injecting Platelet Extract Intravenously.,

Abstract

Injection of a potent extract of rabbit platelets intraven. into normal rabbits failed to induce intravascular clotting or to produce any other demonstrable effect such as lowering the fibrinogen level, even though the amt. injd. was equivalent to more than that of the total circulating platelets. A much smaller quantity of tissue extract (rabbit brain extract) quickly killed the animals by causing extensive intraven. clotting. These findings are in agreement with the hypothesis that the platelet factor does not react with thromboplastinogen until the latter has been activated by thrombin.