Gastric mucosal barrier: hydrophobic lining to the lumen of the stomach

Abstract

The contact angle subtended between a droplet of aqueous fluid and nonwettable surfaces provides a direct estimation of their degree of hydrophobicity. The mean contact angle recorded in dogs at the oxyntic mucosal surface was 85.2 degrees, a value characteristic of acid-resistant substances such as polyethylene. This indicates that the mucosal surface of the stomach has a hydrophobic lining that may be attributed to the surface-active phospholipids known to be present in both the gastric mucosa and juice. Barrier breakers such as bile and aspirin were found virtually to eliminate the hydrophobicity. Hydrophobicity was found to be different in the esophagus, antrum, proximal and distal duodenum, and the colon but consistent with their resistance to acid attack. Endogenous surfactants are discussed for their capability to provide a cohesive and strongly adsorbed protective monolayer--a physical model for the gastric mucosal barrier compatible with the major properties of the gastric lining and many features of ulcerogenesis, including the protection afforded by prostaglandins.

Surface Hydrophobicity Properties of Rabbit Stomach In Vitro

“…Hills el a/. (43) found that tissue from the oxyntic region of canine stomach was more hydrophobic than the antral mucosa. In contrast to the higher surface hydrophobicity of mucosa from the body of dog stomach, mucus from the same region was hydrophilic in nature (44).…”

NSAID injury to the gastrointestinal tract: evidence that NSAIDs interact with phospholipids to weaken the hydrophobic surface barrier and induce the formation of unstable pores in membranes

“…Our laboratory originally proposed that the barrier properties of the stomach, and perhaps other regions of the gastrointestinal tract, exposed to noxious luminal agents is attributable, in part, to it's unique hydrophobic characteristics that makes it non-wettable to luminal acid and other aqueous damaging agents (Hills et al 1983;Lichtenberger 1995). Furthermore, we proposed and provided evidence for the hypothesis that this biophysical barrier property was dependent on the ability of mucus cells to secrete surfactant-like phospholipids that form extracellular layers, perhaps a monolayer, that adsorbs directly to the luminal interface of the mucus gel layer or the plasmalemmal membrane itself (Figure 1) (Goddard & Lichtenberger 1987;Lichtenberger 1995Lichtenberger , 2001).…”

Intestinal surfactant-like material. A novel secretory product of the rat enterocyte.

“…The nature of the mucosal cytoprotective barrier has extensively been studied in the stomach ofdogs and rats, and a phospholipid-containing product identified in lumenal contents was visualized on the surface of rat stomach (7,8). Because the lumenal contents showed surface-lowering activities, these findings suggested an analogy with pulmonary surfactant.…”