Cytochalasin D enhances shear-induced platelet aggregation.

(A) Washed platelets (1.5 × 10⁸/mL) were incubated with either vehicle alone (−CD, i) or 5 μmol/L CD (+CD, ii) in the presence of HvWf (10 μg/mL). Platelets were then exposed to the indicated shear rates in a cone-and-plate viscometer as described under “Materials and methods.” Platelets were then fixed, stained with 1 μmol/L DiOC₆, mounted onto glass slides, and subjected to confocal microscopy (20 × objective). The 3-dimensional images of aggregated platelets were reconstructed using Voxblast (Vaytek Inc). Results presented are from 1 experiment, representative of 5 independent experiments. (B) Platelet aggregates from 8 random fields (10 × objective) were subjected to volumetric analysis, and the extent of aggregation was expressed as the fold increase in the volume of aggregates over that detected for Me₂SO-treated control platelets. Results are the mean ± SE from 5 experiments. ░, buffer; ▪, 5 μmol/L CD.