Degradation of ¹²⁵I-TFPI in serum and fibrin clot from normal or AT-depleted plasma. Radiolabeled rTFPI was mixed with plasma, and coagulation was induced by the addition of tissue factor and Ca²⁺, as described in Materials and Methods. After 20 hours, the serum and fibrin clot were separated and subjected to autoradiographic analysis. (Lane 1), intact rTFPI; (lane 2), rTFPI treated with thrombin; (lane 3), rTFPI incubated with normal plasma; (lane 4), rTFPI in serum from normal plasma; (lane 5), rTFPI in serum from AT-depleted plasma; (lane 6), rTFPI in fibrin clot from normal plasma; (lane 7), rTFPI in fibrin clot from AT-depleted plasma.