Phospholipids, Proteins and Platelet-Lipoid

Abstract

THE time taken for Russell viper venom to accelerate the clotting of fasting human plasma poor in platelets—the Stypven time—is relatively long. The addition of very small quantities of some active phospholipids^1,2 to this system produces a shortening of the Stypven time, and the shortening is proportional to the quantity added. It may be concluded that there is very little available active phospholipid in fasting platelet-poor plasma. A simple phospholipid extraction of fasting platelet-poor plasma yields a material that greatly accelerates the Stypven time of platelet-poor plasma. It is concluded that there are molecules of active phospholipids in plasma, but that they are ‘unavailable’ for this test and presumably are bound in the plasma proteins.