<prompt> Maximum reabsorption of HCO3 - occurs inPCTDCTCDLoop of henle  <response>: The process of bicarbonate reabsorption occurs predominantly in the proximal tubule about 90. The rest occur in the thick ascending limb and in the collecting tubule. All involve hydrogen ion secretionRef: Ganong;s Review of Medical Physiology, 23rd edition, page no: 680 