Role of GPIIb-IIIa in thrombin-induced platelet procoagulant activity.
(A) Gel-filtered platelets were preincubated with 1 μmol/L GRGDS or with 20 μg/mL 7E3 for 10 minutes and activated with thrombin (0.05-2 U/mL), and gel-filtered platelets from a patient with Glanzmann thrombasthenia were activated with thrombin (0.05-2 U/mL); ● indicates 25 000 control platelets/μL; ○, 25 000 platelets/μL in presence of GRGDS; ■, 25 000 platelets/μL in presence of 7E3; ▵, 25 000 platelets/μL from a patient with Glanzmann thrombasthenia. The fluorescence of 5000 platelets per measuring point was determined by flow cytometry. (B) Thrombin generation by the prothrombinase complex on resting and thrombin-activated (0.5 U/mL) gel-filtered platelets and thrombin-activated (0.5 U/mL) gel-filtered platelets after pretreatment with 20 μmol/L 7E3 in the presence of 0.4 U/mL factor Xa and 6 μmol/L CaCl2; ○ indicates 25 000 platelets/μL; ●, 25 000 platelets/μL activated with thrombin; ■, 25 000 platelets/μL, pretreated with 7E3, activated with thrombin. Data are the mean of 3 experiments using platelets from different donors.
