Fibrinolytic activity of rat plasma during development of Guerin epithelioma

Fibrinolytic activity in the blood of rats during the development of Guerin epithelioma was studied. It was measured by means of radiometric method, based on the amount of plasmin degradation products released from 125I-fibrin, as well as by means of amidolytic technique with the use of Chromozym PL. During the initial phase of epithelioma development the fibrinolytic activity of plasma, determined after inactivating plasma proteinase inhibitors, increases. It also increases in the euglobulin fraction. Simultaneously, the content of fibrin(ogen) degradation products (FDP) increases in the blood. During the stage of the intensive development of neoplastic disease fibrinolytic activity as well as plasminogen activator activity become inhibited, whereas the concentration of FDP retains the level observed in healthy animals. Inhibition of fibrinolytic activity in the later phase of the disease coincides with the appearance of low-molecular weight antifibrinolytic factor in the blood of rats loaded with epithelioma.