STUDIES ON THE FUNCTIONALITY OF NEWLY SYNTHESIZED FIBRINOGEN AFTER TREATMENT OF ACUTE MYOCARDIAL-INFARCTION WITH STREPTOKINASE, INCREASE INTHE RATE OF FIBRINOPEPTIDE RELEASE

In 15 patients with acute myocardial infarction who received 1,500,000 U of streptokinase, the gradual appearance of newly synthesized fibri nogen and the fibrinopeptide release during the first 35 h after SK tr eatment were evaluated. At 5 h the fibrinogen circulating in plasma wa s observed as the high molecular weight fraction (HMW-Fg). The concent ration of HMW-Fg increased continuously, and at 20 h reached values hi gher than those obtained from normal plasma. HMW-Fg represented about 95% of the total fibrinogen during the first 35 h. The degree of phosp horylation of patient fibrinogen increased from 30% before treatment t o 65% during the first 5 h, and then slowly declined to 50% at 35 h. T he early rates of fibrinopeptide A (FPA) and phosphorylated fibrinopep tide A (FPAp) release are higher in patient fibrinogen than in isolate d normal HMW-Fg and normal fibrinogen after thrombin addition. The ear ly rate of fibrinopeptide B (FPB) release is the same for the three fi brinogen groups. However, the late rate of FPB release is higher in pa tient fibrinogen than in normal HMW-Fg and normal fibrinogen. Therefor e, the newly synthesized fibrinogen clots faster than fibrinogen in th e normal steady state. In two of the 15 patients who had occluded coro nary arteries after SK treatment the HMW-Fg and FPAp levels increased as compared with the 13 patients who had patent coronary arteries, The se results provide some support for the idea that an increased synthes is of fibrinogen in circulation may result in a procoagulant tendency. If this is so, the HMW-Fg and FPAp content may serve as a risk index for thrombosis.