Effect of PAR1 inhibition on P-selectin expression, Annexin V binding, platelets adhesion, and fibrin generation. (A) Whole blood was pre-incubated with increasing concentrations of selective nonpeptide PAR1 receptor inhibitor SCH 79797 and then stimulated with PF4 and KKO. The data are expressed as inhibition of platelet stimulation when samples pre-incubated with the PAR1 inhibitor were compared with samples pre-incubated with vehicle. N = 3, each in duplicate. One sample t tests were used to determine the significance of inhibition when compared with 1, no inhibition. *P < .05; **P < .01; ***P < .005. (B-C) Microfluidic studies were completed using human whole blood where platelet accretion (B) is represented as AUC over 15 minutes and fibrin deposition (C) as the sum of the relative fluorescent units. Samples were pre-incubated with 10 µM SCH 79797 or vehicle, and then stimulated with PF4 and KKO or isotype control antibody TRA. Data are presented as mean ± SEM. N = 9 in both (B-C). All samples were run in parallel and paired t tests were employed on the raw data to assess significance.