Adhesion of transgenic mouse platelets to VWF under high shear conditions. (A) Transgenic mouse blood was perfused over human VWF at a rate of 1800 s⁻¹, followed by incremental increases in shear rate to a maximum of 20 000 s⁻¹. Quantitation of the number of adherent platelets at each shear rate demonstrated a significant reduction in the number of hGPIbα^FW platelets able to remain adherent at shear rates of 10 000 s⁻¹ and above compared with hGPIbα^WT as mean (± SEM) for n = 6 experiments. *P < .05. (B) Rolling velocity was analyzed from the same experiments as in panel A. At shear rates of 3000 s⁻¹ and above, hGPIbα^FW platelets rolled significantly faster that hGPIbα^WT platelets for n = 6 experiments. *P < .05, **P < .01. Note that the rolling velocity at 20 000 s⁻¹ was not significantly different because there were too few hGPIbα^FW platelets remaining adherent to analyze. (C) Transgenic mouse blood was perfused over human VWF at 5000, 10 000, or 20 000 s⁻¹ and the number of platelets adhering from the bulk flow was quantitated over at least 5 fields as the mean (± SEM) from 3 independent experiments. There was no significant difference between the number of adherent hGPIbα^WT and hGPIbα^FW platelets at any of the shear rates tested.