Effect of LNAENNA on platelet aggregation as a function of thrombin concentration. The extent of platelet aggregation, stimulated by α-thrombin at concentrations from 0.2 to 4 nmol/L, was measured in the presence (▪) and absence (•) of 400 μmol/L LNAENNA. Maximum platelet aggregation in the absence of the peptide was observed between 1 and 2 nmol/L thrombin and the results normalized with 2 nmol/L thrombin equal to 100%.