Loss of Vascular Fibrinolytic Activity Following Irradiation of the Liver: An Aspect of Late Radiation Damage

The vascular fibrinolytic activity, known to originate from the endothelium, was studied histochemically by fibrinolysis autography in liver samples from beagles exposed to radiation treatment. Eighteen to thirty months prior to sacrifice, six dogs received X irradiation (4600 rad in 5 weeks) and three dogs received X irradiation plus aspirin (1 g/kg). Two dogs served as untreated controls. Control livers showed extensive fibrinolytic activity related to large and small vascular structures. The vascular fibrinolytic activity had been lost from all vessels except the major portal branches in five irradiated livers and was severely diminished in three. One irradiated liver appeared to possess normal fibrinolytic activity.