00184.2013.-Endothelin- 1 (ET-1) is the most potent vasoconstrictor peptide known. It exerts its actions through two pharmacologically different receptors: ETA and ETB receptors. In the renal vasculature, there is a majority of ETB receptors in the efferent arteriole, whereas a greater amount of ETA receptors are located in the afferent arteriole. The nephron is rich in ETB receptors, especially in the thick ascending limb and collecting ducts, while containing a smaller amount of ETA receptors. High levels of circulating or renal ET-1 have been described in cardiovascular diseases such as hypertension or diabetes, diseases also associated to renal inflammation. Despite extensive evidence associating high levels of ET-1 to increased renal inflammation, the molecular mechanism(s) by which ET-1 leads to renal immune infiltration and/or immune activation remains unknown. In this minireview, we propose that the ET-1/ETA pathway mediates an increase in renal endoplasmic reticulum (ER) stress, initially a survival mechanism that if prolonged, leads to the eventual death of the cell via apoptosis. © 2013 the American Physiological Society.