Endothelin and endothelial dysfunction.

Nitric oxide (NO) and endothelin (ET) produced in endothelial cells are leading molecules which regulate vascular function. Failure of the physiological balance between these two molecules is usually referred to as endothelial dysfunction. ET was initially identified as a potent vasoconstrictive peptide. Three ET isoforms and two ET receptors have been identified. One of the isoforms, ET-1, plays a significant role in many cardiovascular diseases. On the other hand, oxidized low-density lipoprotein (oxLDL) is known to induce endothelial dysfunction. The endothelial receptor for oxLDL was cloned, and named lectin-like oxidized receptor-1 (LOX-1). Activation of LOX-1 generates reactive oxygen species (ROS), and acivates a transcriptional factor, nuclear factor κB (NFκB), resulting in down-regulation of NO and up-regulation of ET-1. LOX-1 might be a key molecule in the generation of endothelial dysfunction. In endothelial dysfunction, ET-1 is an aggravating factor of cardiovascular diseases.