Zinc inhibits FPA release and increases fibrin turbidity.

Physiologic concentrations of Zn(II) (4-40 microM) can increase the rate of thrombin-induced fibrin clot formation (decreased clotting time, CT) and increase the turbidity of the fibrin gel. Both the initial and ultimate turbidity (AbS 600 nm) of fibrin gels are increased in the presence of Zn(II). Two techniques were used to elaborate the mechanisms of Zn+2 procoagulant effect. Analytical ultracentrifugation indicates that Zn(II) does not induce the formation of fibrinogen multimers. Radioimmunoassay for FPA indicates that thrombin activation of fibrinogen is decreased by Zn(II), with 50% inhibition of FPA release observed at 35 microM Zn(II). These experiments indicate that the critical feature of Zn(II) procoagulant effect is not due to the induction of fibrinogen proteolysis by thrombin, which is actually decreased. Rather, it appears that Zn(II) accelerates the polymerization step of fibrin assembly and concomitantly modifies fibrin gel structure.