Microelectrode determination of oxyntic cell pH in intact frog gastric mucosa. Effect of histamine

Debellis, L.; Curci, S.; Frömter, E.

Pflugers Archiv European Journal of Physiology 422(3): 253-259

1992


ISSN/ISBN: 0031-6768
PMID: 1488284
DOI: 10.1007/bf00376210
Accession: 009021027

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Abstract
Intracellular pH (pH-i) of acid-secreting cells was measured in intact gastric fundus mucosa of Rana esculenta with double-barrelled pH microelectrodes. Tissues were mounted, serosal side up, between two half chambers and individual cells were impaled after microsurgical removal of the serosal muscle layer. Transepithelial potential differences (V-t) and resistance (R-t) as well as serosal cell membrane potential (V-s) and pH-i were continuously recorded at rest (0.1 mmol/l cimetidine) or during stimulation (0.5 mmol/l histamine). During chamber perfusion with HCO-3-/CO-2-buffered Ringer solution of pH-o = 7.36, V-t and R-t were -21.7, SD+-6.0 mV and 229+-83 OMEGA cm-2 (n=17) while V-s and pH-i averaged -57.3+-6.9 mV and 7.4+-0.11 (n=25). The latter value is considerably more alkaline than all recent pH-i measurements obtained with microspectrofluorometric techniques on isolated cells, glands or intact tissue. The difference may in part be explained by use of HCO-3--free solutions in most of the previous studies because we observed that such solutions decrease pH-i to 6.89+-0.18 (n=4). Again, in contrast to recent literature, application of histamine in HCO-3-/CO-2-buffered solution led to further transient alkalinization by 0.12+-0.05 pH unit (n=8). Since in accidental punctures of the gastric gland lumen were noticed that H+ secretion only began approximately 5 min after histamine application, we conclude that the histamine-induced initial alkalinization does not reflect stimulation of the H+/K+ ATPase pump. Alternatively, it may result from histamine-induced activation or inactivation of other ion transporters, one possibility being activation of basolateral Na+/H+ and Cl-/HCO-3- exchangers.

Microelectrode determination of oxyntic cell pH in intact frog gastric mucosa. Effect of histamine