![Fig. 4. Relation between instantaneous velocity and [Ca++]i elevations during platelet interaction with immobilized VWF. / (A) A blood cell suspension was prepared as described in the legend for Figure 2. After addition of the anti-αIIbβ3antibody LJ-CP8 (100 μg/mL) and 2 mM EGTA to chelate extracellular Ca++, the suspension was perfused over immobilized VWF at a shear rate of 3000 seconds−1 for 90 seconds. Interacting platelets were analyzed during the successive 30 seconds. Panel Ai shows movement and fluorescence changes of a representative platelet interacting with the surface during the indicated time interval. The diagrams on the right depict [Ca++]i changes (Aii) and instantaneous velocity (Aiii) of the same platelet observed for 7 seconds. Vertical arrows identify the peak of a type α/β Ca++ elevation (Ca) as well as the preceding (Vb) and following (Va) instantaneous velocity peaks. The mean ± 95% CI of the time intervals between these events, calculated for 15 separate measurements, is shown. In panel Aiii, the horizontal arrow indicates the time interval corresponding to the images in panel Ai. (B) The blood cell suspension contained 2 mM Ca++ and 1 mM Mg++, but no anti-αIIbβ3 antibody and no EGTA. The results, presented as in panel A, show a type γ Ca++ oscillation in a motionless platelet analyzed for 7 seconds. Similar results were observed in more than 100 separate experiments.](https://ash.silverchair-cdn.com/ash/content_public/journal/blood/100/8/10.1182_blood-2002-02-0514/4/h82023252004.jpeg?Expires=1735535633&Signature=HKcMayhNiiVXzqt~sE7Mt4ofA3MuiqvABogF9JPBrh~rhjcOu2bZY2bvIxSYL1uW14WpDEVIFXbjYNsjnJbZ71~10-N60AHJDWDCPIkRlSIyYfCyebDy9ywDa-Gds~xPXZ-qUwGj3udCFwY4qAOlUX3WkuYYZ2U0m-DIkcDkY-1fxEMVctsoCt5DJlzAxO5kawesUY2~4QSlt-4piQObbZjJOVo5T~nEe0s8BTOgB~arKagODMlIYz1U800EH3TA5GhG1VAGcU5NtPPQzH6fLUBv2sNi7jXxI0sp69Ay6HKDx3uWdZFcHqxUUoLIH8Nnc2Tic~CmDgcxMEg0XTcxTQ__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Relation between instantaneous velocity and [Ca++]i elevations during platelet interaction with immobilized VWF.
(A) A blood cell suspension was prepared as described in the legend for Figure 2. After addition of the anti-αIIbβ3antibody LJ-CP8 (100 μg/mL) and 2 mM EGTA to chelate extracellular Ca++, the suspension was perfused over immobilized VWF at a shear rate of 3000 seconds−1 for 90 seconds. Interacting platelets were analyzed during the successive 30 seconds. Panel Ai shows movement and fluorescence changes of a representative platelet interacting with the surface during the indicated time interval. The diagrams on the right depict [Ca++]i changes (Aii) and instantaneous velocity (Aiii) of the same platelet observed for 7 seconds. Vertical arrows identify the peak of a type α/β Ca++ elevation (Ca) as well as the preceding (Vb) and following (Va) instantaneous velocity peaks. The mean ± 95% CI of the time intervals between these events, calculated for 15 separate measurements, is shown. In panel Aiii, the horizontal arrow indicates the time interval corresponding to the images in panel Ai. (B) The blood cell suspension contained 2 mM Ca++ and 1 mM Mg++, but no anti-αIIbβ3 antibody and no EGTA. The results, presented as in panel A, show a type γ Ca++ oscillation in a motionless platelet analyzed for 7 seconds. Similar results were observed in more than 100 separate experiments.
