Effect of EDTA on the activation-independent and shear rate–dependent aggregation and disaggregation of platelets perfused over immobilized VWF. Whole blood containing 93 μM PPACK, 10 μM PG E1, 10 μM mepacrine, and the addition of EDTA (5 mM) from the beginning of flow, was perfused over immobilized VWF at varying wall shear rates. The images shown are single frames from a real-time recording (Video S2). The timeline (black horizontal bar) shows at what moment during the experiment a given image was taken as well as the wall shear rate during different periods of perfusion, as explained in the legend to Figure 1 (A, 50 seconds, 3000 s-1; B, 180 seconds, 13 000 s-1; C, 240 seconds, 15 000 s-1; D, 340 seconds, 17 000 s-1; E, 540 seconds, 3000 s-1; and F, 1020 seconds, 3000 s-1). An arrow at 14 minutes on the timeline indicates when blood without EDTA replaced the blood with EDTA (from the same donor) perfused from the beginning of the experiment. The bar graph shows the average count, length, and area of all the platelet aggregates present in 5 different positions on the surface after 540 seconds (▪) and 1020 seconds (▦) of perfusion under the conditions described. All values are reported as mean ± SEM and differences are statistically significant (count: P < .001; length: P < .001; area: P < .006).
