Factor IXa catalyzes the activation of FX to FXa in the Intrinsic Blood Clotting Pathway.  FIXa, in an isolated experiment, reacts with ATIII to form the IXa-ATIII complex, as observed by quantitative SDS-Page.  Under control conditions, 2.29�0.0 units of complex are formed.  When 1�g of Heparin is preincubated with ATIII for thirty minutes at room temperature, prior to the addition of FIXa, an elevated quantity of complex, 29.4�0.04 units is observed, indicating an anti-coagulant effect.  When 1�g of Protamine Sulfate is preincubated with ATIII at room temperature for thirty minutes prior to the addition of FIXa, no complex is detected (0.0�0.0, p=0.009, n=4), suggesting a procoagulant effect of Protamine Sulfate on this isolated reaction.  When 0.07�g of Spermine is used in lieu of Protamine Sulfate, ratios of 1.09�0.003 (P=0.04, n=4) and 1.21�0.13 (p=0.017, n=4), are observed, indicating a reduction of the formation of the complex, albeit not as profound as Protamine Sulfate.  When 0.05�g of Spermidine or 0.5�g of Spermidine replace Spermine, the respective values are 0.93�0.11 (P=0.13, n=4) and 0.72�0.12 units (p=0.09/0.04, n=4).  Hence, Spermidine as well as Spermine inhibit the FIXa-ATIII complex formation under the test conditions utilized, suggesting a procoagulant effect.  In comparison with the other coagulation enzymes, the Protamine Sulfate, Spermine, and Spermidine exhibit procoagulant effects on FIXa and XIa, while promoting an anticoagulant effect on Thrombin and FXa in their interactions with ATIII.

Procoagulant effect of protamine sulfate on the interaction of the isolated FIXa-antithrombin III reaction

247th National Meeting (2014)

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