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: Physiology
[{'content': 'Various solutes are reabsorbed in the proximal tubule during tubular reabsorption. Which of the following ion is exchanged for H+ in proximal convoluted tubule? \nSelect and explain. \nA. K+, B. Na+, C. HC03, D. CI-', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Na+/H+ exchanger (NHE3) is located in the luminal membrane of the proximal tubule epithelial cell. This transpo system allows Na+ to enter the cell from the tubular lumen in exchange for a proton (H+) from inside the cell. As in all poions of the nephron, Na+/K+-ATPase in the basolateral membrane pumps the reabsorbed Na+ into the interstitium so as to maintain a low intracellular Na+ concentration. The H+ secreted into the lumen combines with bicarbonate (HCO3-) to form H2CO3 (carbonic acid). Ref: Ives H.E. (2012). Chapter 15. Diuretic Agents. In B.G. Katzung, S.B. Masters, A.J. Trevor (Eds), Basic & Clinical Pharmacology, 12e.', 'role': 'assistant'}]