The Na-K-2Cl cotransporter (NKCC2) is a sodium-potassium-chloride cotransporter. It is mainly expressed on the luminal membrane of renal epithelial cells of the thick ascending limb of Henle's loop (TALH) and mediates the majority of NaCl resorption and concentration of urine. NKCC2 is the target for several diuretic drugs, such as bumetanide, and is involved in the pathogenesis of hypertension. Mutations in the NKCC2-encoding gene, SLC12A1, causes Bartter’s syndrome, which is featured by impaired salt reabsorption in the TALH, hypokalemic metabolic alkalosis, and hypercalciuria . Recently, NKCC2 was reported to be expressed in the brain hypothalamo-neurohypophyseal system (HNS) and upregulated upon osmotic stress.