PAR-1 expression after platelet activation.

Boxes represent PAR-1 density quantified by flow cytometry at rest and on PRP stimulation for 15 minutes at 37°C by collagen 100 μg/mL, SFLLRN 100 μM, or U46619 10 μM (final concentrations). To avoid platelet aggregation, PRP was first incubated with 4 μg/mL eptifibatide. Because the response was stable at a 1-week interval, for each subject the mean value of the 2 visits is used. Collagen and SFLLRN induced a small but significant decrease in receptor numbers, from 1262 ± 198 sites at rest to 1125 ± 192 and 1231 ± 215 sites after stimulation by collagen and SFLLRN, respectively. U46619 had no effect (1264 ± 203 sites). Boxes represent the median values with 25th and 75th percentiles, and the bar chart shows 90th and 10th percentiles.