Cleavage of cytoskeletal proteins induces unstable platelet adhesion under shear conditions. (A) Washed human platelets prepared as described in ‘Methods’ were treated with either DMSO, 1μM ABT-737 (ABT), or 50μM Q-VD-OPh 10 minutes before ABT-737 treatment (ABT + QVD), then allowed to adhere to VWF for 10 minutes in the presence of 1 mg/mL ristocetin. Shear rates of 600 or 1800 s−1 were applied for up to 5 minutes, and the number of stationary platelets was analyzed from 5 independent experiments. ***P < .001). (B) Washed human platelets were allowed to adhere to VWF under static conditions in the presence of 1 mg/mL ristocetin for 60 minutes. The number of adherent platelets was analyzed as the mean (± SEM) from 3 experiments. (C) Surface expression of GPIbα was determined by flow cytometry using CD42b-PE anti–human GPIbα mAb as mean (± SEM) from 3 experiments. (D) VWF binding to DMSO, ABT-737, or Q-VD-OPh 10 minutes before ABT-737–treated human platelets was measured in the presence of 5 μg/mL botrocetin as mean (± SEM) from 3 experiments.
