Peripheral tachykinins, EKA/B, stimulate functional responses in platelets. Washed platelets (A,D) or those loaded with the intracellular calcium chelator BAPTA-AM (B), [³H]5-HT (C), or [³H] arachidonic acid (E) were stimulated with vehicle alone (acetic acid 0.001%) or EKA/B. The results represent percentages of platelet aggregation (A,B), percentage of total [³H]-5HT (C), or [³H] arachidonic acid (E) taken up into the platelet and released, or surface fluorescence of PE-conjugated anti-CD62P antibody as a measure of alpha-granule secretion (D). n = 3 (A-C); n = 4 (E); mean plus or minus SEM. *P < .05; **P < .01; ***P < .001. Panel D is representative of 3 separate experiments.