Kinetics of clot contraction in whole blood. Curves tracking changes in the size of contracting clots formed in citrated whole blood. (A) Samples were clotted with 1 U/mL thrombin in the presence of 0, 2, 5, and 10 mM CaCl2. (B) Samples were clotted with 0.5 or 1 U/mL of thrombin and 2 mM CaCl2. (C-F) Samples were clotted with 1 U/mL and 2 mM CaCl2. (C) Myosin IIA was inhibited through the addition of blebbistatin at 25, 50, 100, and 200 μM final concentrations. (D) Fibrin-platelet interactions were impaired by adding RGDS at 0.5, 1, and 2 mM final concentrations. (E, F) Cross-linking of fibrin was suppressed with 1 mM iodoacetamide (E) and 0.1, 0.5, 1.0, and 2.0 mM cystamine (F).