Dependency of shear-induced PMP generation on the GPIb-VWF interaction. Flow cytometric analysis was performed after exposure of citrated PRP to shear rates of 10 s–1 or 10 000 s–1 in a cone-and-plate viscosimeter. In all samples, platelet activation and aggregation was blocked by addition of PGE1, apyrase, and tirofiban. Flow cytometric analysis was performed in PRP (A) or PPP(B). Samples were double-labeled with fluorescein isothiocyanate–conjugated anti-CD41 to show platelet specificity and with phycoerythrin-Cy5–conjugated annexin V to determine phosphatidyl serine expression. Exposure to high shear rates increased PMPs with phosphatidyl serine membrane expression. Blocking the GPIb-VWF interaction with NMC-4 completely inhibited generation of PMP.
