Changes in Clot Retraction Time and Platelet Adhesiveness Following Whole Body Irradiation. ∗

Abstract

Conclusions

1. There is an inhibition of platelet adhesiveness and a prolongation of clot retraction time following whole body radiation of the dog. These changes are demonstrable 3 days after radiation, prior to thrombocytopenia or prolongation of clotting time which is associated with hemorrhage. 2. Inhibition of clot retraction time can be reversed in vitro by addition of excesses of calcium. This suggests a defect in the radiated animal in the use of calcium in initiation of clot retraction. 3. There is a substance in the plasma of the radiated dog which acts on platelets to decrease platelet adhesiveness and inhibit clot retraction time. This factor is not demonstrable before 8th post radiation day and is most easily shown when the animal is thrombocytopenic.