Figure 3. Losartan and cinanserin demonstrate selectivity for GPVI.

Ca²⁺ release and aggregations were carried out with 5 μM of the P₂Y₁₂ receptor agonist 2-MeSADP (a, Ca²⁺ release and b, aggregation), or 0.5 U/ml of the PAR1 and PAR4 receptor agonist thrombin (c, Ca²⁺ release and d, aggregation). Losartan (⧫); cinanserin (▴), n = 3, ± SEM. For global tyrosine phosphorylation, washed human platelets were incubated with drug or vehicle alone before addition of 1 µg/ml CRP-XL or collagen. Samples were collected at 10, 30, 60 or 90 seconds (as indicated by the graduated bars with time increasing to the right) in ice cold 2× lysis buffer and separated on 4–12% NuPage gels under reducing conditions. Tyrosine phosphorylation was visualized with 4G10 anti-phosphotyrosine antibody. Losartan and cinanserin reduce CRP-XL- (e) and collagen-(f) induced global tyrosine phosphorylation, but have no effect on thrombin or 2-MeSADP induced global tyrosine phosphorylation (g). Both drugs reduce FcRγ phosphorylation (h), (unphosphorylated, lower band; phosphorylated, upper band).