The Source of Carbon Dioxide for Gastric Acid Production

Abstract

The source of carbon dioxide for the chemical reaction leading to the production of gastric acid is unknown. The decarboxylation of an amino acid releases carbon dioxide. Pepsinogens provide a rich source of the amino acid arginine. Both the source of carbon dioxide, arginine, and the consequence of arginine decarboxylation, agmatine, have been studied. The site of carbon dioxide production has been related to the survival of the parietal cell. An immunohistochemical study has been carried out on glycol methacrylate embedded gastric biopsies from the normal stomach of 38 adult patients. The sections have been stained using polyclonal antibody to pepsinogen II, polyclonal antibody to agmatine, and polyclonal antibody to Helicobacter pylori. Pepsinogen II and agmatine are found in the parietal cell canaliculi. This is consistent with the production of carbon dioxide from arginine in the parietal cell canaliculi. Evidence is presented for the decarboxylation of arginine derived from the activation segment of pepsinogen as the source of carbon dioxide for the production of gastric acid. The production of carbon dioxide by the decarboxylation of arginine in the parietal cell canaliculus enables the extracellular hydration of carbon dioxide at the known site of carbonic anhydrase activity. The extracellular production of acid in the canaliculus together with the presence of agmatine helps to explain why the parietal cells are not destroyed during the formation of gastric acid. Agmatine is found in the mucus secreting cells of the stomach and its role in acid protection of the stomach is discussed. Anat Rec, 2009. © 2008 Wiley‐Liss, Inc.

Potential of in vivo real-time gastric gas profiling: a pilot evaluation of heat-stress and modulating dietary cinnamon effect in an animal model

“…The trend of the changes in CO 2 defined by the gastric gas profiler is similar to that obtained from measurements in a respiration chamber 43 44 , indicating that the gastric CO 2 production is mainly attributable to the chemical reactions in the acidic environment of the stomach 45 . This is also likely to be accompanied by products of aerobic metabolism of amino acids obtained from protein digestion, which are then chemically decarboxylated into CO 2 gas 46 . The concomitant rise in gastric temperature is likely to be attributed to metabolic heat generation from the chemical reaction as a result of the protein digestion 47 .…”

“…In the present study, this is confirmed by the rise in gastric pH and the reduction of pepsin seen in the Raman spectrum. Such a reduction of gastric acid and pepsin secretion eventually leads to a lowered gastric CO 2 and metabolic heat production, because gastric CO 2 is mainly produced from the chemical reaction of food in an acidic environment together with the decarboxylation of amino acids upon protein digestion 45 46 . These are all related to the concentrations of both gastric acid and pepsin.…”

Expression of ODC Antizyme Inhibitor 2 (AZIN2) in Human Secretory Cells and Tissues

“…This includes several members of the Rab family of GTPases [ 23 ], SNARE proteins and secretory carrier membrane proteins. In addition to a regulatory influence on the vesicle transport it is tempting to speculate, that AZIN2 locally activates ODC that by decarboxylation of ornithine generates CO2 and hereby provides CO2 required for production of gastric acid [ 24 ].…”

Environmental Determinants of Transformation Efficiency in Helicobacter pylori

“…In the live mouse, for example, the partial O 2 pressure (pO 2 ) in the stomach is estimated at 58 Ϯ 15 torr (ϳ7.6%) (20). O 2 and CO 2 concentrations are variable within the gastric environment and can be affected by disease state, food consumption, and location within the gastric mucosa (21,22). For example, the CO 2 concentration tends to be low nearest the epithelium (where the pH is high) and higher toward the gastric lumen (where the pH is low).…”