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).