COMPARATIVE INVESTIGATION ON THE PROTEOLYSIS OF CANINE AND HUMAN FIBRINOGEN INDUCED BY PLASMIN

To verify the sensitivity and specifity of commercial latex reagents to canine fibrinogen degradation products (FDP) as well as for investigations concerning the influence of canine FDP on different in vitro tests of haemostasis, the isolation of the individual canine fibrinogen fragments would be essential. This requires knowledge of the time course of the in vitro-degradation of canine fibrinogen by plasmin. For this reason canine and in comparison human fibrinogen were degraded in the present study by the addition of different acitivities of plasmin (0.1 or 0.2 CU/mg fibrinogen) or plasminogen and urokinase (0.1 CU plasminogen and 50 U urokinase or 0.2 CU and 100 U/mg fibrinogen), respectively. The degradation kinetics was stopped at 18 points of time (5 s-360 min) by addition of aprotinin. Non-reducing SDS-PAGE was used for the analytical separation of FDP at the different points of time. Only small differences between the molecular weights of the resulting fibrinogen fragments in dogs and humans were seen (molecular weights (kD): fibrinogen: 342 (dog)/340 (human), fragment X1-4/1-3: 254-319/255-315, Y1: 196/191, Y2: 156/146, D1-4: 85 112/79-104, E1-4: 44 52/49 55, F1-7/1-6: 31-42/29-40). Using identical activities of human plasmin the degradation kinetics of canine fibrinogen approximated to that of human, too.