Figure 4.

PAR4 inhibitors diminish platelet-leukocyte interactions and platelet alpha granule release in whole baboon (Papio anubis) blood. Whole baboon blood was pretreated with the PAR1 inhibitor SCH 79797 (3 μM), PAR4 inhibitors VU0652925 (10 μM) and VU0661245 (10 μM), or vehicle (0.2% DMSO), then stimulated with the agonists PAR4 AP (activating peptide, 200 μM), TRAP-6 (1 mM), or CRP (10 μg/ml) and stained with markers for leukocytes (CD45), platelets (CD41), and activated platelets (CD62P). (A) All samples were gated for platelets by CD41+ and granulocytes by CD45+ and high side scatter (SSC, granularity). (B) Granulocytes (CD45+, high SSC) were plotted against CD41, and a line was drawn to designate the CD41+ region. Platelets (CD41+) are shown for comparison. Bar graphs designate (C) percent of CD41+ granulocytes and (D) percent of activated (CD62P+) platelets for each treatment. Basal = no agonist; n ≥ 3–4 independent experiments; * designates p < 0.05 versus vehicle.