Effect of the myosin II inhibitor (blebbistatin) on thrombus consolidation in vitro. Lepirudin-anticoagulated human whole blood was preincubated with blebbistatin, or an inactive enantiomer of blebbistatin (control), prior to perfusion through collagen-coated microslides at 1800 s⁻¹, as described in “Two-dimensional quantification of thrombus consolidation.” (A) Snapshots of individual thrombi over a time period of 1.5 minutes were obtained off-line. These images are taken from 1 representative of 3 independent experiments. (B) Whole blood spiked with DiIC₁₂-labeled platelets was perfused through collagen-coated microslides at 1800 s⁻¹, and the distance between firmly adherent platelets quantified, as described in “Two-dimensional quantification of thrombus consolidation.” Results represent the mean plus or minus SEM (n = 3; ns P > .05; **P < .005; ***P < .001).