text: To determine whether arginases modulate the endothelial NO synthesis, we investigated the effects of the competitive << arginase >> inhibitor [[ N(omega)-hydroxy-nor-L-arginine ]] (Nor-NOHA) on the activity of NOS, arginases, and L-arginine transporter and on NO release at surface of human umbilical vein endothelial cells (HUVECs).