In vitro effects of hydrochloric acid and various concentrations of acetic, propionic, butyric, or valeric acids on bioelectric properties of equine gastric squamous mucosa.
OBJECTIVE
To compare the effects of hydrochloric acid (HCl) and various concentrations of volatile fatty acids (VFAs) on tissue bioelectric properties of equine stomach nonglandular (NG) mucosa.


METHODS
Gastric tissues obtained from 48 adult horses.


METHODS
NG gastric mucosa was studied by use of Ussing chambers. Short-circuit current (Isc) and potential difference (PD) were measured and electrical resistance (R) and conductance calculated for tissues after addition of HCl and VFAs (5, 10, 20, and 40 mM) in normal Ringer's solution (NRS).


RESULTS
Mucosa exposed to HCl in NRS (pH of 1.5 and, to a lesser extent, 4.0) had a significant decrease in Isc, PD, and R, whereas tissues exposed to acetic acid at a pH of < 4.0, propionic and butyric acids at a pH of <or= 4.0, and valeric acid at a pH of <or= 7.0 induced a concentration-dependent effect on reduction in these same values. Values for Isc returned to baseline (recovery of sodium transport) after addition of calcium carbonate in tissues exposed to all concentrations of VFAs except the higher concentrations of valeric acid at a pH of <or= 4.0. Histologic examination revealed cell swelling in the mucosal layers below and adjacent to the stratum corneum in tissues exposed to HCl and VFAs at a pH of <or= 4.0.


CONCLUSIONS
The VFAs, especially acetic acid, in the presence of HCl at a pH of <or= 4.0 appear to be important in the pathogenesis of NG mucosal ulcers in horses.
Andrews
Frank M
FM
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996, USA.
Buchanan
Benjamin R
BR
Smith
Sionagh H
SH
Elliott
Sarah B
SB
Saxton
Arnold M
AM
D019342:Acetic Acid / Q000378:metabolism / Q000633:toxicity; D000704:Analysis of Variance; D000818:Animals; D020148:Butyric Acid / Q000378:metabolism / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D004553:Electric Conductivity; D017097:Electric Impedance; D005232:Fatty Acids, Volatile / Q000378:metabolism / Q000633:toxicity*; D005753:Gastric Mucosa / Q000187:drug effects*; D006736:Horses / Q000378:metabolism*; D006851:Hydrochloric Acid / Q000378:metabolism / Q000633:toxicity*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D010421:Pentanoic Acids / Q000378:metabolism / Q000633:toxicity; D011422:Propionates / Q000378:metabolism / Q000633:toxicity
D005232:Fatty Acids, Volatile; D010421:Pentanoic Acids; D011422:Propionates; D020148:Butyric Acid; C038780:n-pentanoic acid; D019342:Acetic Acid; D006851:Hydrochloric Acid