**Abstract**

Endothelial cell dysfunction has lately become one of the principal subjects being incorporated into the assessment of cardiovascular risk because of the relevance that has been shown in several clinical studies. Comprehending and incorporating basic physiological knowledge, about endothelium molecular biology and vascular tonicity, is key to understanding the relevance of this topic. The approach of endothelial dysfunction physiopathology is overly complex and widely studied, but it can be enrolled into both consumption of bioavailable NO and deficit production of NO. In the last decades, scientific equipment has been developed from the necessity of creating non-invasive tools to measure arterial stiffness, being FMD one of the first and most used ones. Once the endothelial cell dysfunction was identified, several drugs and bioactive substances were evaluated because of their potential to decrease the level of arterial stiffness and improve life quality, such as polyphenols, phosphodiesterase five inhibitors, and new incoming therapies.

**Keywords:** endothelial cell dysfunction, nitric oxide, flow mediated dilatation, polyphenols, PDE5i
