This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
[{'content': 'In Bartters syndrome there is defect in \nSelect and explain. \nA. DCT, B. Thick ascending limb of LOH, C. PCT, D. Descending limb of LOH', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ref. Guyton. 13th edition. Page. 1103\nNa+--K+--2Cl- transporter \nThis is an electro neutral transport resulting in the reabsorption of about 25% of the filtered sodium, chloride, and potassium.\n\nThe 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). \u2028\nThis 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. \u2028\n\nBartter’s syndrome\n\nIt is a genetic mutation resulting in diminished function of the Na+--K+--2Cl- transporter in Ascending loop of Henle\nThis leads to a low volume state, which causes an increase in renin and aldosterone (know as a secondary hyperaldosteronism).\nPatients exhibit hypokalemia, alkalosis, and elevated urine calcium.', 'role': 'assistant'}]