Effects of platelet SR-BI deficiency on the platelet reactivity, platelet cholesterol content, and platelet counts in normolipidemic conditions of WT mice. (A-B) Platelets in PRP in panel A or isolated by gel filtration in panel B from chimeric WT mice with SR-BI^−/− BM or WT BM were stimulated with ADP, PAR4-AP, thrombin, or convulxin (CVX), and platelet integrin α_IIbβ₃ activation was assessed by FACS analysis. (C-D) Platelet aggregation in PRP isolated from chimeric WT mice with SR-BI^−/− BM or WT BM was induced by ADP (5μM), convulxin (500 ng/mL), or PAR4-AP (150μM) and was optically monitored. (C) Quantification of the aggregation data. Data are expressed as maximal amplitude of aggregation within 5 minutes after adding the agonist. (D) Representative aggregation curves are shown. (E) Platelet cholesterol contents for chimeric WT mice with WT or SR-BI^−/− BM. Platelets were stained with 50 μg/mL filipin and analyzed by flow cytometry. (F) Platelet counts in whole blood collected from chimeric WT mice with SR-BI^−/− BM or WT BM. Data are presented as mean ± SEM of at least 3 independent experiments *P < .05, **P < .01.