Principal site of acidification of urine ______

Principal site of acidification of urine is collecting duct. Acidification occurs in both distal tubule and collecting duct, but collecting duct, but collecting duct is more impoant. The urinary pH of 4.5 (limiting pH) is normally reached in the collecting ducts. In the late distal tubules and collecting ducts, the tubular epithelium secretes H+ by primary active transpo. Primary active secretion of H+ occurs in type A intercalated cells of the late distal tubule and in the collecting tubules. H+ concentration can be increased as much as 900-fold in the collecting tubules. Ref: Guyton and Hall 13th edition Pgno: 417, 418