Objective—To determine the effect of pH with or
without pepsin or taurocholic acid on the bioelectric
properties of gastric squamous mucosa in horses.
Sample Population—Gastric tissues obtained from
16 adult horses that did not have evidence of gastric
Procedure—Bioelectric properties of squamous
mucosa were determined, using modified Ussing
chambers. Tissues then were exposed to mucosal
pepsin (1 mg/ml) or taurocholic acid (2.5 mM) under
neutral (pH 7.4) or acidic (pH 1.7) conditions.
Results—Exposure of mucosal sheets to an acidic pH
resulted in an immediate and sustained decrease in
transmembrane potential difference and calculated
tissue resistance. Pepsin or taurocholic acid did not
significantly affect bioelectric variables when added to
a mucosal bath solution of pH 7.4. A synergistic effect
between pepsin or taurocholic acid and mucosal acidification
was not detected.
Conclusions and Clinical Relevance—Mucosal acidification
with or without pepsin or taurocholic acid
resulted in reduced tissue resistance. These data support
the contention that squamous erosions or ulcers
in horses are mediated, in part, by prolonged exposure
of gastric squamous mucosa to luminal acid.
(Am J Vet Res 2002;63:744–749).