Résumé : Decreased endothelial Nitric oxide (NO) bioavailability is one of the earliest events of endothelial dysfunction. Assessment of microvascular blood flow using a Laser Doppler Imager during local noninvasive administration of L-N-Arginine-Methyl-Ester (L-NAME) by skin iontophoresis may help discriminate the relative contributions of NO and non-NO pathways during a skin thermal hyperemic test.