Studies on Fibrin Formation and Effects of Dextran

Summary In this study highly reproducible turbidimetric techniques are used to investigate clotting of human platelet-poor plasma and purified human fibrinogen solutions by thrombin. Three phases are clearly distinguishable turbidimetrically during clotting. All the three phases are altered by dextran. This effect of dextran is not mediated by any action on the enzymatic activity of thrombin. Further, it is independent of the molecular weight of dextran, but is found related to the final dextran, thrombin and fibrinogen concentrations. Evidence is presented to show that dextran accelerates the polymerisation of fibrin monomer. However, it seems clear that dextran has an additional action quite apart from this effect. These actions of dextran are discussed in relation to kinetics of clot formation.