Hyperthermia stimulates plasminogen activator inhibitor type 1 expression in human umbilical vein endothelial cells in vitro.

The effect of exposure to hyperthermia on the fibrinolytic potential of human umbilical vein endothelial cells (HUVEC) in culture was studied. HUVEC responded to exposure to 42 degrees C with a time-dependent increase in plasminogen activator inhibitor type 1 (PAI-1) activity and antigen accompanied by a four- to fivefold increase in PAI-1 specific m-RNA and a decrease in tissue-type plasminogen activator (t-PA) antigen. The effect of 8 hours exposure to hyperthermia on PAI-1 activity and antigen could not be reversed by reexposure of the cells to 37 degrees C for 24 hours as evidenced by continuously increased amounts of PAI-1 released into the conditioned media. t-PA release, however, decreased during the 24-hour period at 37 degrees C after exposure to hyperthermia. No difference in PAI-1 antigen present in the extracellular matrix of heat treated HUVEC as compared to HUVEC kept at 37 degrees C could be found. Our data supports the idea that hyperthermia is one stress factor that influences the fibrinolytic potential of endothelial cells.