Plasmin generation by tPA, but not SK, is decreased in Aβ-influenced clots during clotting and lysis. (A) Fibrinogen, plasminogen, tPA, thrombin, CaCl₂, and Pefa-5329 or vehicle were mixed with or without 3μM Aβ₄₂ as described in “Enzyme activity.” Absorbance was measured at 350 nm to follow clot formation and lysis and at 405 nm to monitor plasmin activity. Curves of A₄₀₅ without Pefa-5329 were subtracted from Pefa-5329 A₄₀₅ curves to control for A₄₀₅ arising from clot turbidity and not plasmin activity. (B) Half-lysis of tPA/plasminogen-lysed clots was delayed in the presence of Aβ compared with control (P = .011). (C) Same as panel A, except SK was substituted for tPA. (D) Half-lysis of SK/plasminogen-lysed clots was delayed in the presence of Aβ compared with control (P = .005).