REN and hypertensive disorder: Several studies have revealed that increased reactive oxygen species (ROS) generated by nicotinamide adenine dinucleotide phosphate [NAD(P)H] oxidase, following activation of type 1 receptor (AT1R) by Angiotensin-(Ang) II, the main peptide of the Renin–Angiotensin–Aldosterone System (RAAS), is the central mechanism involved in Ang-II-derived hypertension.