The Role of L-arginine in the Endothelial Dysfunction

Each subject will be exposed to three treatments, a) 5 g of L-arginine, b) 15 g of L-arginine, and c) placebo, the sequences will be randomly assigned to the 42 volunteers. The washout period between interventions will be from one to two days.L-arginine will be mixed in 60 cc of dextrose-based syrup to blind the taste and color of the L-arginine powder.

Ultrasound from the brachial artery will be done on 3 occasions: at 9 pm after 4hs of fasting, at 6 am and at 11 am. The brachial artery images will be acquired above the antecubital fossa in the longitudinal plane of the artery with an ultrasound machine using a 6-MHz linear transducer. Flow-mediated vasodilatation will be assessed by the reactive hyperemia method (inflation of a blood pressure cuff around the forearm to 200 mmHg for 5 minutes and then released). The diameter of the brachial artery will be assessed 60 to 90 s after deflation of the cuff. After a 10min period a second baseline image of the brachial artery will be obtained. Non-low-mediated vasodilatation will be measured by an administration of a sublingual dose of nitroglycerin (0.4 mg).