Microelectrode measurements of K+ and pH in rabbit gastric glands: effect of histamine.
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.
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D000632:Aminopyrine / Q000378:metabolism; D000818:Animals; D001562:Benzimidazoles / Q000494:pharmacology; D005750:Gastric Juice / Q000378:metabolism*; D005753:Gastric Mucosa / Q000378:metabolism*; D006632:Histamine / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D008564:Membrane Potentials; D008839:Microelectrodes; D009853:Omeprazole / Q000031:analogs & derivatives*; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000502:physiology*; D011817:Rabbits
D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D001562:Benzimidazoles; D000632:Aminopyrine; D010042:Ouabain; D006632:Histamine; D009853:Omeprazole; D011188:Potassium; C028887:picoprazole; D015056:1-Methyl-3-isobutylxanthine