A Computer Assisted Method to Obtain the Prothrombin Activation Velocity in Whole Plasma Independent of Thrombin Decay Processes

A method is described that, on the basis of the time course of amidolytic activity after the triggering of thrombin generation in normal plasma, allows the calculation of the velocity of prothrom-bin conversion independent of thrombin inactivating processes. It is shown how the reaction constants for the o2M-dependent and the o2M-independent thrombin inactivation processes can be obtained in a sample of whole plasma. The method is verified by demonstrating that the experimen-tally observed time courses of residual prothrombin and of o2M-thrombin complex coincide with those calculated from the time course of amidolytic activity, and by showing that the course of prothrombin conversion in plasma without ct2-macroglobulin or AT III is adequately described if the u2M or AT Ill-dependent breakdown constants are taken zero in the calculations. It appears that the inactivation of thrombin, endogenousl