Involvement of the Gut Chemosensory System in the Regulation of Colonic Anion Secretion

Figure 1

Schematic diagram of secretion stimulated by short-chain fatty acids in colonic epithelial cells. At the basolateral membrane, enters the cell from the basolateral space across the , cotransporter (NKCC1). , -ATPase causes drainage of , and leaves via the channel. also moves to the apical side paracellularly. The cystic fibrosis transmembrane conductance regulator (CFTR), which is located on the apical membrane, allows to exit the cell. The colonic epithelium CFTR conductance is constitutively active [1]. Luminal SCFAs stimulate the FFA2/3 receptors located on the apical membrane, which in turn activate second messenger pathways to induce ACh release from epithelial cells basolaterally. The released ACh activates muscarinic receptors located on the basolateral membrane of epithelial cells, inducing secretion.