Short-term treatment with L-arginine prevents the smoking-induced impairment of endothelial function and vascular elastic properties in young individuals

Background l-arginine, the substrate for endothelial nitric oxide synthase, is essential for normal endothelial function. Aim of the present study was to investigate in healthy smokers the effect of a short-term daily l-arginine administration on vascular function. Methods We studied the effect of a 3-day oral administration of l-arginine in 10 healthy smokers (24.3 ± 0.73 years old) on 3 occasions (day0, day1 and day3). The study was carried out on two separate arms, one with l-arginine (7 gr/d) and one with placebo according to a randomized, placebo-controlled, double-blind, cross-over design. Measurements were carried out before, immediately after (Sm0) and 20 min after (Sm20) cigarette smoking. Endothelial function was evaluated by flow-mediated dilatation (FMD) of the brachial artery. Carotid-femoral pulse wave velocity (PWV) was measured as an index of aortic stiffness and augmentation index (AIx) as a measure of arterial wave reflections. Results Compared to placebo, l-arginine led to an increase of FMD (p < 0.05 at day 2), indicating a favorable effect on endothelial function, which however lost significance at day 3. l-arginine induced a progressive decrease of PWV and AIx at both day 2 and day 3 (p < 0.01 vs baseline for all). l-arginine blunted the acute smoking-induced increase of AIx at both day 1 (p < 0.05) and day 3 (p < 0.01), and there was a trend to protect the smoking-induced change of PWV at day 3 (p < 0.1). Conclusions Short-term daily administration of l-arginine improves arterial performance in healthy smokers and abrogates the smoking-induced increase in arterial stiffness and wave reflections in these individuals.