AJP - Gastrointestinal and Liver Physiology, Vol 248, Issue 4 443-G449, Copyright © 1985 by American Physiological Society
Effect of Ag+ on isolated bullfrog gastric mucosa
P. K. Rangachari and J. Matthews
In nitrate solutions, Ag+ added to the luminal side had marked effects on
transmucosal conductance and potential difference (PD). Conductance
increased quickly (85% within 60 s, 420% by 10 min); PD increased initially
(11% within 30 s) and then fell precipitously (58% decreased within 2 min,
85% decreased by 10 min). During this period, no increase in mannitol
permeability was found. These changes were essentially similar in
histamine-stimulated, spontaneously secreting, and metiamide-inhibited
fundic mucosae. Replacement of luminal Na+ by choline had no effect on the
changes observed. Similar changes occurred also in the antrum. In SO2-4
media the increases in conductance occurred more slowly (40% within 2 min,
150% after 10 min); PD increased initially for 4-6 min and then slowly
declined over 60 min to 74% of control values. After Ag+ treatment,
replacement of luminal SO2-4 by nitrate led to an inversion of the PD by up
to 20 mV (serosa -ve). Brief exposure of the mucosa (2 min) to Ag+ did not
show any obvious damage, although surface cells were damaged following more
prolonged exposures. After a 4-min treatment with Ag+, electrical and
secretory parameters showed substantial recoveries. Ag+ appears to increase
anion conductance; these effects appear to occur on the apical membranes of
tubular and/or surface cells of the fundus and antrum.
