Activation of Prothrombin by Platelets Plus Globulin. ∗

Abstract

Summary

1. Twice-washed platelets were relatively stable in the presence of calcium ions and in contact with glass.

2. In the presence of calcium, washed rabbit platelets plus a small amount of bovine globulin activated bovine prothrombin. Activation was much slower with platelets alone, and no activation was detected with the globulin alone.

3. Water-clear platelet extracts could be substituted for platelet suspensions in this test system. In such case, the presence of the globulin was still necessary for prompt activation of prothrombin.