In vitro primate gastric mucosa: electrical characteristics

Area of Science:

• Physiology
• Gastroenterology
• Ion Transport

Background:

• Understanding ion transport in gastric mucosa is crucial for comprehending gastric physiology and disease.
• Previous studies have explored various aspects of gastric ion transport, but detailed characterization under specific conditions is ongoing.

Purpose of the Study:

• To assess ion transport in isolated rhesus gastric mucosa under conditions minimizing oxygen diffusion limitation.
• To investigate the roles of sodium (Na+) and chloride (Cl-) ions, amiloride, and ouabain in regulating gastric ion transport.

Main Methods:

• Isolated rhesus gastric mucosa was used, with bathing solutions modified by substituting Na+ and Cl- with less permeable ions.
• The effects of amiloride and ouabain on ion transport were examined.
• Net fluxes of 22Na were estimated using methods to overcome tissue variability.

Main Results:

• The gastric mucosa generated a potential difference of 51.3 mV (serosal positive) with a conductance of 5.56 mS/cm².
• Low paracellular conductance (32%) and passive chloride permeability were identified as major contributors to overall conductance.
• Amiloride-sensitive Na+ entry and ouabain-sensitive Na+ exit were observed, with Na+ absorption and Cl- secretion contributing equally to the short-circuit current.

Conclusions:

• The rhesus gastric epithelium exhibits significant passive chloride permeability, contributing substantially to its conductance.
• Active sodium absorption and active chloride secretion are key processes driving short-circuit current in this model.
• Specific drug sensitivities highlight distinct pathways for Na+ and Cl- transport across the gastric mucosa.