Thromboxane A2 generation by human umbilical endothelial cells

Human umbilical endothelial cells were examined for their ability to release thromboxane A2 (TXA2) and prostacyclin (PGI2). We could show that the basal, unstimulated release of the two eicosanoids was inversely related to the cell density. At a density of 100,000 cells/cm2 TXA2 release was 0.062 +/- 0.28 fg/cell/h and PGI2 release was 0.184 +/- 0.051 fg/cell/h, whereas at a cell density of 20,000 cells/cm2 the cells released 1.075 +/- 0.055 fg TXA2/cell/h and 1.653 +/- 0.09 fg PGI2/cell/h. In stimulation experiments ATP and ADP significantly (p less than 0.001) increased the TXA2 and the PGI2 release. ANF caused a slow but still significant (p less than 0.001) enhancement of TXA2 release. Thrombin and ionophore A23187 caused the strongest stimulatory response, resulting in a significantly (p less than 0.001) increased release of both eicosanoids.