Thrombin induces Egr-1 mRNA in primary endothelial cells.

HPAECs were grown on 6-well plates and starved overnight in EBM-2 medium containing 0.5% FBS. The cells were treated in the absence or presence of thrombin at the doses and for the times indicated and subsequently harvested for total RNA. RNase protection assays were carried out with α-[³²P] UTP–labeled Egr-1 and β-actin probes as described in “Materials and methods.” Densitometry was used to calculate the ratio of Egr-1 and β-actin signals. The results are expressed as fold induction relative to control untreated cells. The data represent the means and standard deviations from 3 independent experiments. (A) HPAECs were incubated in the absence (Control) or presence of 1.5 U/mL thrombin, 10 ng/mL TRAP, 5 U/mL hirudin, or 1.5 U/mL thrombin plus hirudin (1.5-5 U/mL) for 1 hour. *P < .01 relative to control untreated cells. (B) HPAECs were incubated in the absence (“C” indicates control) or presence of 1.5 U/mL thrombin for the times indicated. (Panel C) HPAECs were incubated in the absence (“C” indicates control) or presence of thrombin for 1 hour at the doses indicated.