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Gastrointestinal Motility Monitor (GIMM)
Published on: December 1, 2010
Gastric HCO3--secretion in the guinea pig
The American Journal of Physiology
|June 1, 1978
Summary
Gastric bicarbonate (HCO3-) secretion neutralizes stomach acid (H+), protecting the gastric lining. This study quantifies acid and bicarbonate secretion in guinea pigs, revealing bicarbonate
Area of Science:
- Gastroenterology
- Physiology
Background:
- Gastric acid (H+) secretion is crucial for digestion but can damage the stomach lining.
- Bicarbonate (HCO3-) secretion is a key protective mechanism in the stomach.
Purpose of the Study:
- To simultaneously measure gastric H+ and HCO3- secretion in anesthetized guinea pigs.
- To investigate the regulation of gastric HCO3- secretion by carbachol and histamine H2-receptor antagonists.
Main Methods:
- Measurement of gastric intraluminal PCO2 and pH.
- Inhibition of acid secretion using cimetidine or metiamide.
- Stimulation of secretion with carbachol and atropine.
Main Results:
- Quantitative agreement between CO2 release and HCO3- decrease after HCl instillation.
- Basal HCO3- secretion was lower than H+ secretion, but net output became alkaline after H2-receptor antagonist administration.
- Carbachol stimulated both H+ and HCO3- secretion; only H+ secretion was histamine antagonist-sensitive.
- Atropine blocked carbachol-stimulated HCO3- secretion but not basal HCO3- output.
- Increased HCO3- secretion correlated with increased Na+ and Cl- influx.
Conclusions:
- Gastric HCO3- neutralizes intraluminal acid at the mucosal surface, likely protecting against acid damage.
- HCO3- secretion is regulated by cholinergic pathways, while H+ secretion is modulated by histamine.
- Simultaneous measurement of PCO2 and pH provides a reliable method for assessing gastric acid-base balance.
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