Argatroban inhibition of thrombin present in aged plasma clots treated with alteplase. Plasma clots were formed and aged for 3 hours and then incubated with alteplase (10 μg/mL) before permeation with argatroban and determination of thrombin activity. The experimental procedures described in the legend to Fig 6 were followed, except that alteplase was used to induce lysis rather than streptokinase. Data obtained with alteplase-lysed plasma clots (•) and intact plasma clots (○) were analyzed with equation 2 to obtain the solid lines; the resultant inhibition parameters are cited in Table3. Data obtained with alteplase-treated plasma (△) provide a measure of amidolytic activity due to plasmin, as described in the text. (Insert) Time course of alteplase lysis of aged plasma clots. Experimental procedures and data analyses described in the legend to Fig 4 were followed, except that clots were overlaid with alteplase (10 μg/mL) to induce lysis.