Bicarbonate secretion

Bicarbonate secretion is a fundamental physiological process rather than a single molecular target. It involves the coordinated action of various epithelial cells in the pancreas, duodenum, biliary tract, and kidneys to release bicarbonate ions (HCO3-) into the lumen or bloodstream to maintain acid-base homeostasis and regulate pH levels [7, 12]. This process is essential for neutralizing gastric acid in the small intestine, facilitating the optimal environment for digestive enzymes, and protecting mucosal surfaces from acidic injury [1, 7]. At the molecular level, it is mediated by a complex network of proteins including the cystic fibrosis transmembrane conductance regulator (CFTR), several members of the Solute Carrier (SLC) family like SLC4A4 and SLC26A6, and carbonic anhydrase enzymes that catalyze the hydration of carbon dioxide to produce bicarbonate [1, 10, 12]. Dysregulation of this process is central to the pathophysiology of diseases like cystic fibrosis, chronic pancreatitis, and peptic ulcer disease [1, 13]. Therapeutic strategies often involve modulating the specific proteins that drive this process, such as using CFTR potentiators to enhance secretion or carbonic anhydrase inhibitors to reduce it for conditions like glaucoma or altitude sickness [11, 13].

Other names

HCO3- secretionEpithelial bicarbonate transportPancreatic bicarbonate secretionDuodenal bicarbonate secretionAlkaline secretion

Bicarbonate secretion is modulated by drugs that either inhibit carbonic anhydrase enzymes (decreasing bicarbonate production), activate or potentiate the CFTR anion channel (increasing apical bicarbonate efflux), or stimulate receptors like guanylate cyclase-C or the secretin receptor to increase intracellular secondary messengers like cAMP and cGMP, which drive the activity of various transporters [1, 11, 13].