In vitro anticoagulant assays. (A) aPTT assays of HCII^+/+ (solid symbols) or HCII^-/- (open symbols) mouse plasma were performed in the presence of glycosaminoglycans at the final concentrations indicated. Circles indicate porcine intestinal heparin; squares, porcine skin dermatan sulfate; triangles, S plicata dermatan sulfate; and diamonds, A nigra dermatan sulfate. (B) Purified mouse thrombin (16 nM) and mouse antithrombin (50 nM) were incubated in the presence of glycosaminoglycans for 60 seconds, and the remaining thrombin activity was determined by hydrolysis of a chromogenic substrate. The dashed line indicates the activity of thrombin in buffer alone. Symbols are as defined in panel A.