Evidence for surfactant contributing to the gastric mucosal barrier of the horse.

The research article explores the hydrophobic properties of the equine stomach lining and posits that this characteristic, influenced by surface-active phospholipids, contributes to the stomach’s natural defense mechanism against acid back-diffusion.

Objective of the Study

• The main aim of the research was to examine the hydrophobicity, or water-repelling abilities, of the equine stomach lining, and study the ultrastructure that lends this attribute.

Methodology

• Gastric and duodenal mucosal samples were collected post-euthanasia from 5 horses for surface contact angle measurements using a goniometer. This device is typically used to measure the angle where a liquid interfaces with a solid, like the surface of a stomach lining.
• Samples from 4 horses and a foal were also examined under electron microscopy after a fixation process that helped preserve phospholipids and oligolamellar structures. These are essential components of the stomach lining that play crucial roles in digestion and barrier protection.

Results

• The researchers observed through goniometer measurements that the contact angles for the equine gastric glandular mucosal surface were significantly greater than those for the duodenum, indicating a more hydrophobic nature.
• They also noted that contact angles for gastric squamous tissue tended to be greater than those for the duodenum, reinforcing the stomach’s hydrophobic character.
• Electron microscopy revealed abundant osmiophilic phospholipid material, which can be identified as surfactant within both squamous and glandular gastric mucosae – contributing to the observed hydrophobicity.

Conclusion

• Based on the results, the researchers proposed that the hydrophobic nature of the stomach, driven by phospholipids adsorbed to the surface, enhances the stomach’s ‘gastric mucosal barrier’, which is central to preventing the back-diffusion of acid.
• They also suggested that phospholipids may play an additional role in acid defense by lining intracellular canaliculi and oxyntic ducts, areas where other protective mechanisms might be absent.