Platelet aggregation and fibrinogen binding. (A) Platelet aggregation in platelet-rich plasma was stimulated with ADP or PAR4 receptor-activating peptide (AYPGKF). Results are representative of at least 3 experiments, performed in duplicate on at least 4 animals from each genotype. (B) Specific FITC-fibrinogen binding to platelets was assessed by flow cytometry. Fibrinogen binding is reported as mean fluorescence intensity in arbitrary fluorescence units and was normalized for αIIbβ3 surface expression measured with antibody to αIIb. *P ≤ .05 compared with wild-type platelets. (C) Specific fibrinogen binding in the absence (□) and presence (■) of 0.5 mM MnCl2. Results in B and C are representative of at least 6 independent experiments for each genotype.
