Studies on platelet plasma membranes. III. Membrane glycoprotein loss from circulating platelets in rabbits: inhibition by aspirin-dipyridamole and acceleration by thrombin.

DD125ISA, which binds to platelet surface glycoproteins, is lost more rapidly from double-labeled circulating rabbit platelets than is 51Cr, a label of platelet cytoplasm. Treatment of rabbits with aspirin and dipyridamole to diminish platelet function did not affect 51Cr survival but inhibited DD125ISA loss so that it disappeared from the circulation at the same rate as 51Cr . Intravenous thrombin infusion increased DD125ISA loss relative to 51Cr loss. Therefore surface glycoprotein loss was prevented by agents which inhibit platelet function and was accelerated by intravascular coagulation. These observations support the hypothesis that platelet surface glycoprotein loss is a continuous process in the normal circulation which may occur during reversible contact interactions in the process of hemostasis and thrombosis.