Inhibition of platelet aggregation by OxHDL in eNOS^−/−, Akt-1^−/−, and Akt-2^−/− platelets. Platelets prepared from eNOS^−/− (A), Akt-1^−/− (B), or Akt-2^−/− (C) mice by gel filtration were preincubated with or without SR-BI blocking antibody, followed by incubation with 200 μg/mL murine OxHDL for 5 minutes at 37°C and stimulation with 0.1 U/mL thrombin. Platelet aggregation was monitored. (D) Data from panels A-C are presented as means plus or minus SD of 3 independent experiments. (E) Human platelets isolated by gel filtration were incubated with 200 μg/mL human OxHDL for 5 minutes at 37°C and stimulated with either 0.1 U/mL thrombin or 100 nM PMA. Platelet aggregation was monitored. (F) Data from panel E are presented as means plus or minus SD of 3 independent experiments. NA indicates no addition; α-SR-BI, anti–SR-BI blocking antibody. *P < .005; **P < .001.