Platelet PAR-1 expression and function according to the PAR-1 IVSn−14 A/T polymorphism.

(A) Distribution of PAR-1 levels according to the genotype. Left, A/A homozygotes (74 subjects). Right, A/T heterozygotes (24 subjects) and T/T homozygotes (2 subjects). A/A homozygotes had a significantly higher PAR-1 level (1297 ± 186 sites) than carriers of at least one T allele (A/T and T/T subjects, 1164 ± 203 sites). (B) Relation between PAR-1 receptor numbers and aggregation responses to SFLLRN according to the genotype. PAR-1 numbers correlate negatively with the platelet response to SFLLRN. Double-wave aggregation occurred with 9.1 ± 2.1 μM SFLLRN in A/A subjects (left) and with 10.9 ± 3.0 μM SFLLRN in A/T and T/T subjects. (C) Platelet secretory response to SFLLRN according to the genotype. On SFLLRN (100 μM) platelet stimulation, higher P-selectin expression was observed in carriers of 2 A alleles (11 548 ± 1735 sites) than in A/T and T/T subjects (10 160 ± 2117 sites). Boxes represent the median values with 25th and 75th percentiles and the bar chart shows 90th and 10th percentiles.