This adipokine exhibits nicotinamide phosphoribosyltransferase (NAMPT) activity, and as an intracellular form (iNAMPT) maintains the activity of NAD-dependent enzymes, such as sirtuin 1 [19], while the extracellular form (eNAMPT) can induce inflammation and endothelial dysfunction [32]. Here, SIRT1 is linked to endothelial dysfunction.