In vitro effects of hydrochloric and lactic acids on bioelectric properties of equine gastric squamous mucosa.
Authors: Andrews F M, Buchanan B R, Elliott S B, Al Jassim R A M, McGowan C M, Saxton A M
Journal: Equine veterinary journal
Summary
# Editorial Summary Researchers from five institutions investigated whether lactic acid—a bacterial fermentation byproduct increasingly implicated in equine gastric ulcer syndrome (EGUS)—directly damages the squamous mucosa through bioelectric mechanisms, using tissue samples from 13 horses mounted in Ussing chambers to measure ionic transport and electrical resistance. When exposed to hydrochloric acid at physiological concentrations (pH 1.5–4.0), the mucosa showed significant reductions in short-circuit current and potential difference, with histological evidence of acid-induced damage; lactic acid alone, however, produced no additional harmful effects beyond those attributable to the acid environment itself, even at high concentrations (40 mmol/l). The findings suggest that whilst lactic acid is chemically present in the stomach and capable of contributing to acidosis, it may not be the primary driver of nonglandular mucosal injury through direct toxic mechanisms—instead, the overall acid burden (pH) appears more critical than the specific acid type. For practitioners managing EGUS, this implies that dietary strategies aimed at buffering gastric pH and stabilising the microbial population warrant priority, since reducing acid load itself, rather than targeting lactic acid production specifically, may represent the most effective protective mechanism for the squamous mucosa.
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Practical Takeaways
- •Gastric pH management is critical in preventing nonglandular ulcers; both hydrochloric and lactic acid cause mucosal bioelectric dysfunction at acidic pH levels
- •Dietary management to control fermentation byproducts and maintain gastric pH above 4.0 may help protect squamous mucosa from ulcer development
- •The reversibility of bioelectric changes at neutral pH suggests early intervention to neutralize stomach acid and reduce bacterial fermentation could prevent permanent mucosal damage
Key Findings
- •HCl at pH 1.5 and pH 4.0 significantly decreased short-circuit current and potential difference in equine gastric mucosa
- •Lactic acid at concentrations of 5, 10, and 20 mmol/l produced similar bioelectric changes to HCl when pH was lowered to 1.5
- •High concentration lactic acid (40 mmol/l) showed increased conductance at pH 1.5 but this was not statistically significant
- •Bioelectric changes were reversible when solutions returned to pH 7.0, with histological damage consistent with acid-induced injury at pH <4.0