Relative Roles of Principal and Intercalated Cells in the Regulation of Sodium Balance and Blood Pressure

The kidney continuously adapts daily renal excretion of NaCl to match dietary intakes in order to maintain the NaCl content of the body, and keep vascular volume constant. Any situation that leads to NaCl retention favors a rise in blood pressure. The aldosterone-sensitive distal nephron, which contains two main types of cells, principal (PC) and intercalated (IC) cells, is an important site for the final regulation of urinary Na+ excretion. Research over the past 20 years established a paradigm in which PCs are the exclusive site of Na+ absorption while ICs are solely dedicated to acid-base transport. Recent studies have revealed the unexpected importance of ICs for NaCl reabsorption. Here, we review the mechanisms of Na+ and Cl-transport in the aldosterone-sensitive distal nephron, with emphasis on the role of ICs in maintaining NaCl balance and normal blood pressure.