The Regulation of Gastric Acid Secretion
THE REGULATION OF GASTRIC ACID SECRETION
The key player in regulating gastric acid secretion is the H+/K+ ATPase, which is a magnesium-dependent pump. The following are the basic steps of gastric acid production and secretion:
- H+ is generated within the parietal cell from the dissociation of water. Hydroxyl ions rapidly combine with CO2 via carbonic anhydrase.
- HCO3- is transported outside the cell in exchange of chloride (maintains intracellular pH of the parietal cell).
- Cl- and K+ are transported into the lumen, which is necessary for secretion of acid.
- H+ pumped out of the cell and into the lumen in exchange for K+ through a proton pump.
- H+ accumulation generates an osmotic gradient that causes outward diffusion of water, leading to gastric acid production (HCl, KCl), and a small amount of NaCl