VEGF induces VWF release from human aortic endothelial cells. (A) Dose response. HAECs were treated with VEGF for 1 hour. The amount of VWF released from cells into the media was measured by an ELISA (n = 3 ± SD; *P < .05 versus 0 ng/mL; **P < .01 versus 0 ng/mL). (B) Time course. HAECs were incubated with 50 μg/mL VEGF or 1 U/mL thrombin. The amount of VWF released from cells into the media was measured by an ELISA (n = 3 ± SD; error bars too small to be seen; **P < .01 versus control). (C) VEGF induces P-selectin translocation onto surface of endothelial cells. HAECs were treated with 100 ng/mL VEGF for 5 minutes, and the expression of P-selectin on the cell surface was measured by a cell surface ELISA. (n = 3 ± SD; **P < .01 versus control). (D) Soluble Flt-1 inhibits VEGF-induced VWF release from endothelial cells. HAECs were pretreated with sFlt-1 for 30 minutes, and then incubated with 50 ng/mL VEGF for 1 hour. The amount of VWF released from cells into the media was measured by an ELISA (n = 3 ± SD; **P < .01 versus 0 ng/mL sFlt-1). (E) Soluble Flt-1 alone has no effect on VWF release. HAECs were treated with sFlt-1 for 1 hour. The amount of VWF released from cells into the media was measured by an ELISA (n = 3 ± SD).