Peripheral tachykinins signal through the NK1 receptor on platelets. Washed platelets were stimulated with EKA/B (5 μM) (A) or SP (5 μM) (B) in the presence of NK1 antagonist L733060 or vehicle control (Tyrode-HEPES buffer), and aggregation was measured using optical aggregometry. Data represent means plus or minus SEM. (n = 3); *P < .05; **P < .01; ***P < .001.