Human fibrinogen heterogeneity. A study of limited fibrinogen degradation.

Different fibrinogen species were examined in normal plasma following urokinase treatment, in isolated high molecular weight fibrinogen treated with plasmin and in plasma samples from patients with acute myocardial infarction receiving thrombolytic therapy. In normal plasmas two main fibrinogen species (Mr = 340,000 and Mr = 320,000) and an intermediate fragment (Mr = 330,000) were observed. The 340,000 fibrinogen was the most sensitive to degradation; it gave rise to 330,000 and 320,000 species. Degradation of isolated 340,000 fibrinogen was similar to plasma fibrinogen degradation. After thrombolytic therapy in acute myocardial infarction patients, when the plasma fibrinogen decreased near to zero, the new synthesized fibrinogen was 340,000 form. 'In vivo' conversion of 340,000 to 320,000 fibrinogen, associated with the transitory 330,000 form, was observed. The coagulation study of plasma fibrinogen showed that when Mr 340,000 fibrinogen decreased (40%), the gelation rate decreased and lag time increased drastically. The high 340,000 fibrinogen content found in acute myocardial infarction patients gave rise to the hypercoagulable state.