In vitro effects of hydrochloric acid and various concentrations of acetic, propionic, butyric, or valeric acids on bioelectric properties of equine gastric squamous mucosa.

The research investigates the effects of certain types of acids on the bioelectrical properties of horse stomach tissues. Results suggest that these acids, notably acetic acid combined with hydrochloric acid, contribute to stomach ulcers in horses.

Research Methodology

• The gastric tissues used in this study were obtained from 48 adult horses.
• They specifically focused on the nonglandular (NG) mucosa tissue of horse stomachs, typically a site often affected by ulcers.
• These tissues were placed in Ussing chambers, devices commonly used in research to measure the active transport of ions through epithelial tissues.
• They introduced hydrochloric acid (HCl) and different concentrations of volatile fatty acids (VFAs) which include acetic, propionic, butyric and valeric acids to the tissue samples in a saline solution known as normal Ringer’s solution (NRS).
• The response of the tissue to these acidic additions was then observed and measured in terms of short-circuit current (Isc), Potential Difference (PD) and calculated electrical resistance (R) and conductance.

Research Findings

• Tissues exposed to hydrochloric acid underwent significant decrease in Isc, PD, and electrical resistance. A similar effect was observed when tissues were exposed to acetic acid at a pH of less than 4.0.
• Notably, exposure to propionic, butyric, and valeric acids also resulted in a reduction in these values in a concentration-dependent manner when at a pH of 4.0 or less, except for valeric acid which induced this effect at a pH of up to 7.0.
• The values for Isc, indicative of sodium transport activity within the tissue, returned to normal or baseline levels when calcium carbonate was added except in tissues exposed to higher concentrations of valeric acid at a pH of less than or equal to 4.0.
• Histologic exams of the tissues also revealed a swelling of cells within the mucosal layers below and adjacent to the stratum corneum when exposed to hydrochloric acid and the studied volatile fatty acids at pH of 4.0 or less.

Conclusions and Implications

• The paper concludes that the interaction of volatile fatty acids (particularly acetic acid) with hydrochloric acid at pH of 4.0 or less plays a role in the development of nonglandular mucosal ulcers in horses.
• This investigation draws attention to the impact of diet on the overall gastric health of horses as these acids are typically the products of microbial fermentation in the intestines.
• The findings could open opportunities for potential interventions or treatments, such as the use of buffers like calcium carbonate, to alleviate conditions that foster the development of gastric ulcers in horses.