REN and endothelial dysfunction: Objectives: This study investigated the differential effects of potassium (K+) supplementation on blood pressure, renal function, and oxidative stress in two experimental hypertensive rat models: L-NAME-induced (nitric oxide synthase inhibitor-induced hypertension presenting with reduced NO bioavailability, endothelial dysfunction, vasoconstriction) and DOCA-salt-induced hypertension (deoxycorticosterone acetate + salt mimics volume-dependent hypertension of hypermineralocorticoidism, low renin, high sodium retention and severe cardiac fibrosis and oxidative stress).