Platelet procoagulant activity in response to thrombin.
(A) Annexin V-FITC binding to gel-filtered platelets activated with 0.05 to 2 U/mL thrombin (n = 4); ● indicates 25 000 platelets/μL. The fluorescence of 5000 platelets per measuring point was determined by flow cytometry. Insert: aggregation of gel-filtered platelets induced by 0.01 U/mL thrombin. The platelet counts were adjusted to 1 × 108/mL. The data shown are representative of 3 similar experiments. (B) Thrombin generation by prothrombinase complex was measured on resting and thrombin-activated (0.5 U/mL) gel-filtered platelets in the presence of 0.4 U/mL factor Xa and 6 μmol/L CaCl2 (n = 3); ○ indicates 25 000 platelets/μL, ●, 25 000 platelets/μL activated with thrombin. Data are the mean of the indicated number (n) of experiments using platelets from different donors.
