Author(s): Copley AL, King RG
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Abstract In earlier studies using a modified Weissenberg Rheogoniometer, we found decreased rigidity or torque values (tau) in surface layers of heparin plasma, when compared to tau of oxalate plasma from the same blood withdrawal (Thrombosis Res. 1, 1-17, 1972). In subsequent studies of the viscoelasticity of surface layers of highly purified fibrinogen (97-100\% clottability) of human and bovine origin, we found, with some heparins, marked lowering of surface viscous moduli (eta's) and of surface elastic moduli (Gs). With some heparins no changes in tau, eta's and Gs occurred. Certain low molecular weight (LMW) preparations of heparins showed decreases, but some did not. This is also the case with heparins of low and high affinity for antithrombin. Calcium heparin and Ca2+ alone always increased eta's and Gs, when added to the fibrinogen system. N-desulfated heparin both decreased or did not change eta's and Gs. Preparations of fibrinogen in dog plasma, to which sodium heparin was added, resulted in a decrease of tau values. These results appear to emphasize that plasma proteins other than fibrinogen, and other plasma constituents, may affect surface hemorheological values. These findings suggest needed interface studies of fibrinogen systems to which plasma or plasma constituents are added. We found also that other substances, i.e., dextran MW 20,000; dextran sulfate MW 17,000; sodium hyaluronate and depolymerized hyaluronate decreased tau, eta's and Gs markedly. Recent findings in the literature are discussed in relation to thrombogenesis in which fibrinogenin gelation is considered as the initial phase of blood clotting. Fibrinogenin is the new term for initial fibrinogen aggregation and subsequent fibrinogen gelation without thrombin participation. The inhibition of fibrinogenin formation extra vivum is considered to be a valid indicator of antithrombogenic activity of substances which play a significant role in investigations on the therapy and prevention of thrombotic conditions.
This article was published in Thromb Res
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