Regulation Of Soluble Fibrin By Shear Rate

Abstract

The reaction of fibrinogen and thrombin has been carried out in a Couette-flow apparatus over a range of rates of shear from 0-150 s-1 and at pH’s from 6.4 - 6.8. A minimum is found in the rate of formation of insoluble fibrin at shear rates of 30-60 s-1 (well within the physiological range). The position of the minimum is determined by the concentration of reactants. Rate decreases of up to 50% have been observed. Hirudin quenching of thrombin activity shows that formation of fibrin monomer is unaffected by shear rate, hence the effect is due to changes in fibrin aggregation. The same sort of minimum has been observed when a solution of fibrin monomer is made to precipitate by altering pH and ionic strength in shear fields. The release of B-peptide as analyzed by HPLC appears to be less at the minimum.These results are interpreted as resulting from a lowering of the growth of fibrin particles at low shear rate and an increase in nucleation of particles at higher shear rates.