Na+/HCO3 − Cotransporters in the Colonic Epithelium

Introduction The importance of HCO3 − transport in the colonic epithelium is underscored by the multitude of vital functions it has been associated with, including mucosal protection via HCO3 − secretion and intracellular pH (pHi) regulation, Cl− secretion, NaCl absorption, absorption of short-chain fatty acids (SCFAs) as the primary nutrient for the colonocyte, and possibly also mucin unfolding [1]. HCO3 − can leave the cell via apical conductance, Cl−/HCO3 − exchange, or in exchange for SCFAs [2]. Prerequisite for the intracellular presence of HCO3 − are its intracellular generation catalyzed by carbonic anhyd…