Inhibition of thrombin-induced aggregation of human platelets by heparin and antithrombin 3.

Abstract

Heparin aggregated washed platelets in the presence of divalent cations. The aggregation was not significantly influenced by antithrombin III, albumin, or by the presence of serum. The significance of this finding is discussed. Heparin, together with antithrombin III, inhibited the release of platelet adenine nucleotides and also the platelet aggregation induced by thrombin. The inhibition was rapid and progressive. Much higher thrombin concentrations were inhibited than with antithrombin III alone. The inhibition was more pronounced at 37° C than at 19° C, and could not be reversed by addition of polybrene.