Cartoon summarizing data suggesting the endothelium as a “salt sensor” that responds to changes in [Na+], [K+] and flow by altering production of TGF-β, a fibrogenic growth factor that modifies endothelial and smooth muscle function and promotes vascular stiffness, and NO, a vasodilator that also serves as a potential countervailing influence on TGF-β. Macrophage-derived cytokines, such as VEGF-C and TNF-α, and reactive oxygen species may also directly affect endothelia and vascular smooth muscle and contribute to salt sensitivity. Please see text for details.