ABSTRACT
The effects of tumor necrosis factor (TNF) on the activity of plasmogen acitva-tor inhibitor (PAD and the morphology of the cells were observed in the original passage of cultured human umbilical vein endothelial cells (HUVEC). It was found that the TNF effect on the PAI was determined by the dosage of TNF, that is, 500U/ml of TNF could significantly activate PAT activity while 2500U/ml markedly inhibit it. Morphdogical observation canfirmed that 2500U/ml of TNF could injure HUVEC to form a kind of cells whose morphology was quite similar to that of circulating endothelial cells originating from peripheral blood.These findings suggest that TNF can stimulate HUVEC to increase the PAI acivity but too large a dosage of TNF could injure the metabolic function and structure of HUVEC.