WEBLoop diuretics act on the Na + -K + -2Cl − symporter (NKCC2) in the thick ascending limb of the loop of Henle to inhibit sodium, chloride and potassium reabsorption. This is achieved by competing for the Cl − binding site. Loop diuretics also inhibit NKCC2 at macula densa, reducing sodium transported into macula densa cells.