OxLDL induces platelet aggregation, platelet shape change and MLC phosphorylation. (A) Platelets (2.5 × 10⁸/mL) were stimulated with nLDL (50 μg/mL), oxLDL (50 μg/mL), or collagen (10 µg/mL) for 4 minutes under stirring conditions. Shown are representative aggregation traces of 3 separate experiments. (B) Samples were processed as in (A), except that platelets were preincubated with apyrase (2 U/mL), indomethacin (10 µM), and EGTA (1 mM) followed by stimulation with either oxLDL or nLDL (0-200 µg/mL). Traces were recorded for 2 minutes. Shown are representative traces of 3 separate experiments. (C) Platelets (3 × 10⁸/mL) were stimulated with varying concentrations of oxLDL (10-200 µg/mL) or thrombin (0.05 U/mL) for 15 seconds followed by lysis, separation by SDS-PAGE, immunoblot for phospho-MLC^Ser19, and reprobing for β-tubulin. (Ci) Representative blots. (Cii) Densitometric analysis of 3 independent experiments. (D) Platelets were incubated with 50 µg/mL of oxLDL for various time points (15-300 seconds) or thrombin (0.05 U/mL) for 15 seconds before lysis. Samples were then processed as in (C). (Di) Representative blots. (Dii) Densitometric analysis of 3 independent experiments. (Ei) Samples were processed as in (C), except that platelets were stimulated with nLDL. (Eii) Samples were processed as in (D), except that platelets were stimulated with nLDL. All immunoblots are representatives of 3 separate experiments and were carried out in the presence of apyrase (2 U/mL), indomethacin (10 µM), and EGTA (1 mM). Data are expressed as mean ±SEM.