Intercalated Cells: More than pH Regulation

Abstract

The renal collecting duct is the nephron segment where the final urine content of acid equivalents and inorganic ions are determined. The role of two different cell types present in this nephron segment has been determined many years ago: principal cells that express the epithelial sodium channel ENaC and aquaporin 2, regulate electrolyte reabsorption, while intercalated cells, which express acid-base transporters and vacuolar H+-ATPase, maintain an apropriate acid-base balance. Recent evidence challenges this historical view. Rather than having independent and non-overlapping functions, the two cell types in the collecting duct appear to functionally cooperate to regulate acid-base and volume homeostasis via complex paracrine and endocrine interplay. This review summarizes these recent findings.