Increases in platelet intracellular calcium ([Ca²⁺]_i) induced by HOCl-LDL. Platelets (10⁸/mL) loaded with Indo-1 were stimulated in a plastic cuvette with stirring at 37°C in the presence of 1.8 mM extracellular Ca²⁺. The elevation of [Ca²⁺]_i was measured as a fluorescence ratio (400:480) and calibrated using Ca²⁺ standards. (A) Platelets activated with 1 μM ADP for 5 seconds were stimulated with HOCl-LDL (ox-LDL, 1 μg/mL) or control buffer. (B) Platelets were stimulated with low (1 μg/mL) and high (20 μg/mL) doses of HOCl-LDL. (C) Platelets were preincubated with the PKC-specific inhibitor Bis (10 μM) or 0.1% (vol/vol) dimethyl sulfoxide (DMSO) for 5 minutes, before HOCl-LDL (ox-LDL, 1 μg/mL) was added. Traces are representative for 4 experiments (A-B) and 2 experiments (C). The arrowheads indicate the addition of agonists.