“…Endothelial cells from bovine and human blood vessels produce large amounts of PAI-1 [14,15,79,82,91,96,105,145,146], The production of this inhibitor is markedly enhanced by bacterial lipopoly saccharide [147][148][149], muramyl dipeptide [150], the monokines interleukin 1 [149,[151][152][153] and tumor necrosis factor [154,155] , and thrombin [96,109]. Its activity is reduced by activated protein C [91,113] and by high concentrations of thrombin [91,156] , During the hours that the incubations of endothelial cells in vitro usually last, the ratio between the amount of PAs and the amount of PAI-1 determines the actual fibri nolytic activity in the conditioned medium.…”