<prompt> In Bartters syndrome there is defect inDCTThick ascending limb of LOHPCTDescending limb of LOH  <response>: Ref. Guyton. 13th edition. Page. 1103Na--K--2Cl- transporter This is an electro neutral transport resulting in the reabsorption of about 25 of the filtered sodium, chloride, and potassium.The luminal membrane contains a K channel Figure VIII-4-4, allowing diffusion of this ion back into lumen recall that the concentration of K inside cells is very high compared to the extracellular concentration.  This back diffusion of K into the lumen creates a positive luminal potential, which in turn, promotes calcium and magnesium reabsorption about 25 of FL via a paracellular pathway primarily. This positive luminal potential also causes sodium reabsorption via a paracellular pathway.  Bartters syndromeIt is a genetic mutation resulting in diminished function of the Na--K--2Cl- transporter in Ascending loop of HenleThis leads to a low volume state, which causes an increase in renin and aldosterone know as a secondary hyperaldosteronism.Patients exhibit hypokalemia, alkalosis, and elevated urine calcium. 