Summary
The reaction kinetics of the second phase of blood clotting (conversion of fibrinogen
to fibrin) has been studied in euglobulin and thrombin-antithrombin systems. It was
intended to set up relationships that would make mathematical expression of the processes
possible and which would, moreover, help in detecting dynamic and functional relationships
characteristic of the mechanism involved in coagulation.
The experiments have yielded the following results:
1. In the euglobulin solution containing no antithrombin the fibrinogen-thrombin reaction
can be characterized with a constant deviation from the first order kinetics.
2. The process of thrombin inactivation is a reaction of first order in the initial
phase.
3. The two basic processes (clotting by thrombin in euglobulin solution, inactivation
of thrombin in defibrinated plasma) make it possible to predetermine the thrombin
time of citrated plasma. Theoretical and actual clotting times were in good agreement.
4. The thrombin time of plasma can be computed even if thrombin is not introduced
to the system at one stride but gradually, a manner of administration which is a better
imitation of what happening in vivo.
5. In connection with the computation of the “thrombin time” of citrated blood, we
determined experimentally (and expressed by means of a function) the modification
produced by the corpuscular elements of the blood in the reaction between fibrinogen
and thrombin under atraumatic conditions.
