Effect of hydrochloric acid, pepsin, or taurocholate on bioelectric properties of gastric squamous mucosa in horses.
OBJECTIVE
To determine the effect of pH with or without pepsin or taurocholic acid on the bioelectric properties of gastric squamous mucosa in horses.


METHODS
Gastric tissues obtained from 16 adult horses that did not have evidence of gastric disease.


METHODS
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 74) 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
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.
Widenhouse
Tamara Vetro
TV
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville 32610-0136, USA.
Lester
Guy D
GD
Merritt
Alfred M
AM
D000086:Acetazolamide; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D017609:Barium Compounds / Q000494:pharmacology; D002034:Bumetanide / Q000494:pharmacology; D002257:Carbonic Anhydrase Inhibitors / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D005753:Gastric Mucosa / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology*; D006736:Horses / Q000502:physiology*; D006851:Hydrochloric Acid / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D017136:Ion Transport / Q000187:drug effects / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D010042:Ouabain / Q000494:pharmacology; D010434:Pepsin A / Q000494:pharmacology*; D013656:Taurocholic Acid / Q000494:pharmacology*
D017609:Barium Compounds; D002257:Carbonic Anhydrase Inhibitors; D002712:Chlorides; C024986:barium chloride; D002034:Bumetanide; D010042:Ouabain; D013656:Taurocholic Acid; D000584:Amiloride; D010434:Pepsin A; D000086:Acetazolamide; D006851:Hydrochloric Acid