Method for measuring fibrinolytic activity in a single layer of cells

A method has been developed for measuring fibrinolytic activity in a single layer of cells--for example, venous endothelium or peritoneal mesothelium. A single layer of cells was collected on a gelatin disc, incubated on a fibrin plate for 24 h, and the resulting area of lysis measured. This was converted to a measure of fibrinolytic activity expressed in Ploug units of urokinase by reference to areas of lysis created by standard amounts of urokinase placed on similar fibrin plates. The method has been used for measuring fibrinolytic activity in venous endothelium and peritoneal mesothelium and has demonstrated that the activity in a single layer of endothelial cells is only about one-quarter of that in an equivalent area of whole vein wall. It has also shown that peritoneal fibrinolytic activity is reduced after peritoneal trauma. This method maybe useful in the investigation of the fibrinolytic system in a variety of pathological conditions--for example, thrombosis and intraperitoneal adhesions.