Effects of MPαC on VWF binding to GPIb-IX-and VWF-mediated platelet adhesion. (A) Washed human platelets were preincubated with MPαC or control peptides MαC or MαCsc, or DMSO and incubated with ristocetin in the presence (VWF) or absence (control) of VWF. VWF binding was detected using FITC-labeled anti-VWF antibody and flow cytometry. (B) Quantitative data from 3 experiments (mean ± SD). VWF binding index equals total fluorescence/background fluorescence-1. (C) Platelets were preincubated with MPαC or control peptides MαC or MαCsc, or DMSO, and then perfused through VWF-coated capillary tubes. Numbers of adherent platelets were counted at 10 randomly selected time frames and locations (mean ± SD).