AJP - Gastrointestinal and Liver Physiology, Vol 241, Issue 3 227-G234, Copyright © 1981 by American Physiological Society
Organic acid proton donors decrease intestinal secretion caused by enterotoxins
G. W. Forsyth, R. A. Kapitany and D. L. Hamilton
The effects of several weak acids on the secretory actions of cholera toxin
and the heat-stable enterotoxin of Escherichia coli (ST) have been examined
in ligated jejunal loops in weanling pigs. Ascorbic and acetic acids had no
effect, but L-lactic acid reduced the net fluid secretion caused by cholera
toxin. Glutaric acid and p-aminobenzoic acid blocked net fluid secretion
caused by cholera toxin or by ST. Antisecretory effects were pH dependent
for p-aminobenzoic acid in this study and for nicotinic acid in a previous
report (6). At a pH of 5.0, p-aminobenzoic acid treatment increased
lumen-to-blood sodium flux and decreased the blood-to-lumen sodium flux
caused by cholera toxin. These weak acid effects were more marked on fluid
fluxes in enterotoxin-treated loops than in control loops and persisted for
20-30 min after acid removal from loops. These findings are discussed in
terms of requirements for antisecretory activity and possible modes of
action of antisecretory compounds.
