The earliest stage of atherosclerosis is based on endothelial dysfunction (ED) [5, 6], since a well functioning endothelium protects the blood vessels from damage by oxidative stress, by release of anti-coagulant, anti-inflammatory, fibrinolytic and vasodilating agents . ED can be basically defined as an impairment of vasodilatation in response to acetylcholine or hyperemia, both of which induce nitric oxide-dependent vasodilatation.