Activation of the fibrinolytic system.

The fibrinolytic system is activated either directly or indirectly by proteins that convert plasminogen to plasmin in the circulation, within the interstitices, and on the surface of fibrin clots, or both. Agents that activate circulating and clot-bound plasminogen comparably induce a systemic lytic state accompanying clot lysis. Agents that activate plasminogen in the domain of fibrin preferentially exhibit clot selectivity. Fibrinolytic activators are assayed by detection of protein, generally immunologically, or of functional activity, generally by visualization of lysis of fibrin or by spectrophotometric determination of amidolytic activity.