Figure 5. Inhibitory effect of PMQ on agonist-induced ATP-release and surface P-selectin expression in washed human platelets.

(A) Washed platelets (3.0 × 10⁸/ml) were pre-incubated with PMQ (10 μM, 20 μM, and 40 μM) or a solvent control followed by the addition of collagen (0.5 μg/ml) or thrombin (0.04 U/ml) in the ATP-release reaction experiment. Quantification of ATP release (%) was also shown in the right panel. (B) Washed human platelets were pre-incubated with PMQ (10 μM, 20 μM, and 40 μM) at room temperature for 5 min; FITC-conjugated P-selectin was added 5 min after collagen (2.5 μg/ml) or thrombin (0.2 U/ml) stimulation. P-selectin expression was determined by flow cytometry and presented as representative overlay histograms. Quantification of P-selectin expression (%) was also shown in the right panel. Representative overlay histograms were composed with FlowJo version 7.6 (Tree Star Inc., Ashland, OR, USA). The results are expressed as the mean ± SEM of four experiments. * p < 0.05, ** p < 0.01, *** p < 0.001 vs. vehicle.