Cell-surface expression of surrogate markers of platelet activation.

<p>(<b>A</b>) FITC-labeled P-selectin (CD62P) and (<b>B</b>) Alexa Fluor 448-labeled Gp1b show increased and decreased mean fluorescence intensity (unshaded area), respectively, following <i>in vivo</i> 5-HT treatment in contrast to saline-infused littermates (gray shaded area); n = 5–6. Increased staining indicates active exocytosis of alpha-granules in platelet membranes whereas decreased expression of Gp1b is consistent with enhanced platelet-platelet binding in the presence of high 5-HT. The assay was performed in triplicate.