Fig. 1.

Thrombin induces arginase enzyme activity and arginase I promoter. A: arginase activity in rat aortic endothelial cells (RAECs) exposed to thrombin (30 U/ml) at different time points. Increased arginase enzyme activity was observed as early as 1 h after thrombin exposure and reached maximum activity at 4 h, increasing 4.7-fold. n = 3; *P < 0.05 vs. time 0. B: relative luciferase activity in 1 μg DNA-transfected RAECs incubated with vehicle or different concentrations of thrombin for 4 h. Thrombin (10 U/ml) induced a 3.2 ± 1.4-fold increase in luciferase activity compared with control, whereas 30 U/ml of thrombin induced a 6.4 ± 0.5-fold increase. n = 3; *P < 0.05 vs. vehicle (concentration 0).