In vitro effects of hydrochloric and lactic acids on bioelectric properties of equine gastric squamous mucosa.
BACKGROUND
Volatile fatty acids, byproducts of carbohydrate fermentation by resident bacteria, have been implicated in causing nonglandular (NG) gastric ulcers. Lactic acid (LA), also produced by stomach bacteria, may cause gastric ulcers when exposed to the equine NG mucosa.


OBJECTIVE
To investigate the in vitro effects of LA on equine NG mucosa bioelectric properties, sodium transport and tissue resistance.


METHODS
Gastric tissues obtained from 13 mature horses were studied in Ussing chambers. Short-circuit current (Isc) and potential difference (PD) were measured, and electrical resistance (R) and conductance (G) calculated for tissues after addition of HCl and LA (5, 10, 20 and 40 mmol/l) in normal Ringer's solution (NRS).


RESULTS
Mucosa exposed to HCl or LA (5, 10 and 20 mmol/l) in NRS (pH 1.5 and to a lesser extent pH 4.0) had a significant decrease in Isc and PD. Mucosa exposed to a high concentration of LA (40 mmol/l) in NRS (LRS) at pH 1.5 showed an increased G, but this increase was not significant. Values returned to baseline after solutions were returned to pH 7.0. Histological changes were consistent with HCl-induced (pH <4.0) acid damage.


CONCLUSIONS
HCl induced alteration in bioelectric properties of equine NG mucosa whereas addition of LRS did not, other than those changes seen with HCl alone.
Andrews
F M
FM
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, 2407 River Drive, Knoxville, TN 37996, USA.
Buchanan
B R
BR
Elliott
S B
SB
Al Jassim
R A M
RA
McGowan
C M
CM
Saxton
A M
AM
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004553:Electric Conductivity; D017097:Electric Impedance; D005232:Fatty Acids, Volatile / Q000009:adverse effects / Q000378:metabolism; D005260:Female; D005744:Gastric Acid; D005753:Gastric Mucosa / Q000187:drug effects* / Q000473:pathology / Q000502:physiology; D006734:Horse Diseases / Q000209:etiology; D006736:Horses; D006851:Hydrochloric Acid / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000494:pharmacology*; D008297:Male; D012964:Sodium / Q000378:metabolism*; D013270:Stomach / Q000382:microbiology / Q000473:pathology; D013276:Stomach Ulcer / Q000209:etiology / Q000662:veterinary
D005232:Fatty Acids, Volatile; D019344:Lactic Acid; D012964:Sodium; D006851:Hydrochloric Acid