Figure 5.

Clotting is disrupted by urokinase plasminogen activator (uPA) and tranexamic acid (TXA) as assessed by ROTEM or activated partial thromboplastin time (APTT) methods. Panel A shows effects on ROTEM clot formation time following preincubation of blood with 2.5 nmol L⁻¹ tissue plasminogen activator (tPA) or 5 nmol L⁻¹ uPA with 400 μmol L⁻¹ TXA (all single‐point estimates). Panel B shows similar results for APTT with plasma. In both methods, pre‐incubation of up to 90 min with uPA + TXA extended clotting times, but only after many hours of pre‐incubation with tPA + TXA (similar to no additions). Panel C summarizes a series of pre‐incubation experiments using plasma with reduced α₂‐antiplasmin with various additions as shown. uPA or TXA alone had no effect but together abolished clotting after 25 min of pre‐incubation when α₂‐antiplasmin was 40% of normal. The sensitivity of this plasma to uPA + TXA was corrected by replacement of α₂‐antiplasmin. All APTT results shown as means of duplicate determinations ± range.