Effects of DCB (A), bepridil (B), Ro31-8220 (C), or EIPA (D) on ¹²⁵I-fibrinogen binding to platelets stimulated by various agonists. Washed platelets (1 × 10⁵/μL) were suspended in modified Tyrode Hepes buffer containing 1 mmol/L CaCl₂ in the presence of indicated dose (μmol/L) of each inhibitor and stimulated by 20 μmol/L ADP (□), 0.1 U/mL thrombin (○), or 200 nmol/L PMA (▵). Platelets were also pretreated with 10 μg/mL PT25-2 (•) or 10 mmol/L DTT (▪). Relative amounts of bound fibrinogen derived from ¹²⁵I-fibrinogen-binding assay were normalized to a 100% value for fibrinogen binding to platelets stimulated in the absence of inhibitors. Argipidin (final concentration, 5 μmol/L) was added before mixing with¹²⁵I-fibrinogen when platelets were stimulated with thrombin. Results are the mean ± SD from three separate experiments.