Fibrinolytic characteristics of rat bone marrow extract and its variation by gamma-ray irradiation

The purpose of this investigation is to study the enzymatic properties of rat bone marrow extract which exhibits high fibrinolytic activity, and to observe whether or not the activity is influenced by the whole body irradiation. The results were obtained as follows: 1) A high fibrin degradation activity was extracted with 2M KSCN from rat bone marrow, but failed with 0.15M NaCl or 0.88M sucrose. 2) The activity was clearly demonstrated on plasminogen-free fibrin plates, whereas it was not shown on plasminogen-rich fibrin plates. Assumingly, the activity differs with plasminogen activator. 3) The activity was strongly inhibited with STI as well as DFP, while it was bearly inhibited with TLCK, t-AMCHA and Aprotinin. On the bases of above results, the factor extracted from rat bone marrow by us appears to be identical or similar to the factor in the conventional rat spleen recently found by Okamoto and Nagamatsu. 4) The activity of rat bone marrow extract was remarkably decreased by γ-ray whole body irradiation, and the observed tendency was well correlated with the irradiation-induced bone marrow damage. The activity is, therefore, implicated to be a bone marrow cell origin. (author)