AJP - Gastrointestinal and Liver Physiology, Vol 246, Issue 4 433-G444, Copyright © 1984 by American Physiological Society
Microelectrode measurements of K+ and pH in rabbit gastric glands: effect of histamine
K. Kafoglis, S. J. Hersey and J. F. White
Conventional and liquid ion-exchange microelectrodes sensitive to K+ or pH
were used to examine the response of isolated rabbit gastric glands to
histamine. The epithelial cells were impaled across the basolateral
membrane. The membrane potential averaged -6.1 +/- 0.6 mV and was unchanged
after replacement of medium K+, Cl-, or Na+. The intracellular K+ activity
(alpha iK) averaged 41.3 +/- 3.0 mM, indicating K+ accumulation by a factor
of 6.8. Active accumulation of K+ was eliminated by ouabain. In contrast,
histamine increased K+ activity to 55.3 +/- 3.9 mM. This stimulation was
blocked by ouabain. In glands bathed in a Na+-free medium containing
ouabain, addition of histamine elevated alpha iK from 12.5 +/- 0.7 to 17.1
+/- 1.1 mM. Isobutylmethylxanthine (10(-4) M) also elevated alpha iK. When
impaled with pH-sensitive microelectrodes, glands exposed to histamine
exhibited regions of acidity as low as pH 3. Acidification was also
produced by histamine after medium Na+ had been replaced with choline.
Picoprazole (H 149/94) blocked the effects of histamine on alpha iK and
gland pH. The results are consistent with the view that histamine-induced
acid secretion by gastric glands is associated with K+ uptake by a
mechanism that is independent of Na+ transport but is inhibited by
intracellular Na+. This is most likely the H+-K+-ATPase on the secretory
surface of the gland cells. Evidence that some tissue K+ is bound or
compartmentalized is also discussed.
