Hyperfibrinogenemia increases resistance to thrombolysis in vivo. Thrombosis was triggered in the carotid artery of wild-type mice infused with fibrinogen (plasminogen-, fibronectin-, VWF-, and factor XIII-depleted, concentrations indicated in the figure) or vehicle control. After stable occlusion for 5 minutes, mice were infused with TNKase (concentrations indicated in the figure). Blood flow was monitored by flow probe throughout the experiment. Each panel shows data from an individual mouse, representative of at least 2 mice for each condition. Shaded grey area represents the time of FeCl₃ treatment plus time to reacquire flow.