Substrate dependency for HCl secretion by isolated piglet gastric mucosa

Area of Science:

• Physiology
• Biochemistry

Background:

• Gastric acid secretion is vital for digestion and pathogen defense.
• The specific metabolic substrates fueling this process in early life remain under investigation.

Purpose of the Study:

• To investigate the substrate requirements for histamine-stimulated acid secretion in newborn piglet gastric mucosa.
• To compare the efficacy of various metabolic fuels, including carbohydrates and fatty acids, in supporting gastric H+ secretion.

Main Methods:

• Isolated gastric mucosa from newborn piglets was utilized.
• The tissue was bathed in solutions containing different substrates (glucose, acetate, pyruvate, fatty acids) and stimulated with histamine.
• Hydrogen ion (H+) secretory rates were measured under varying substrate concentrations.

Main Results:

• Gastric H+ secretion was absolutely dependent on exogenous substrates.
• Glucose, acetate, and pyruvate effectively sustained secretion, exhibiting saturation kinetics with glucose (Km ≈ 2 mM).
• Short-chain fatty acids supported lower secretory rates, with effectiveness decreasing in the order: butyrate > valerate > hexanoate > propionate.

Conclusions:

• Newborn piglet gastric mucosa preferentially utilizes carbohydrate sources for H+ secretion.
• The findings indicate a crucial role for exogenous substrates, particularly carbohydrates, in gastric acid production.
• The data suggest that fatty acids are unlikely to be essential for the primary H+ secretory mechanism.