AJP - Gastrointestinal and Liver Physiology, Vol 258, Issue 5 815-G824, Copyright © 1990 by American Physiological Society
Influence of Cl- on pH(i) in oxynticopeptic cells of in vitro frog gastric mucosa
A. Yanaka, K. J. Carter, H. H. Lee and W. Silen
Department of Surgery, Beth Israel Hospital, Harvard Medical School, Boston, Massachusetts.
The effect of Cl- on intracellular pH (pH(i)) was studied using sheets of
frog (Rana catesbeiana) fundic mucosa in which oxynticopeptic cells were
selectively loaded with the acetomethoxy ester form of the pH-sensitive
fluorescent dye 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein
(BCECF/AM). Before the measurement of pH(i), tissues were exposed to either
10(-5) M forskolin in the serosal solution (stimulated tissues) or 3 x
10(-4) omeprazole in the serosal solution (inhibited tissues). In HCO3- and
N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) buffers, pH(i)
increased significantly after removal of Cl- from serosal and luminal
solution, both in stimulated and inhibited tissues. The presence of Cl- in
the luminal solution prevented this rise in pHi, an effect abolished by
serosal 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS, 3 x 10(-4)
M) but not by serosal amiloride (10(-3)M). In the presence of serosal Cl-,
pH(i) increased after exposure to serosal DIDS, more prominently in the
stimulated than in the inhibited tissues. These results confirm the
presence of a Cl(-)-HCO3-exchanger in the basolateral membrane of
oxynticopeptic cells in intact sheets of mucosa and suggest that luminal
Cl- contributes to the regulation of pH(i) in oxynticopeptic cells.
