Kir2.1 K+ Channels of the Gastric Parietal Cell
The purpose of this article is to review the literature regarding the characteristics of the gastric parietal cell apical membrane K+ channel and provide new evidence that suggests that the inward rectifying K+ channel, Kir2.1, may be involved in K+ recycling at the apical membrane of the gastric parietal cell. It has been previously reported that gastric H+/K+ ATPase-containing vesicles exhibit a 10 pS K+ channel when measured in planar lipid bilayers. The native gastric K+ channel in these vesicles is insensitive to ATP, is active in the absence of Ca2+, is stable at an extracellular pH of 3.0, and is activated by PKA. A literature search suggested that Kir2.1 has many of the properties of this channel. This is the first report to show that recombinant rabbit Kir2.1 K+ channels are active in the presence of ATP, in the absence of Ca2+, and are stable at an extracellular pH of 3.0. Preliminary results demonstrate that Kir2.1 is also PKA activated. Kir2.1 also exhibits single channel currents that are of similar magnitude as the native channel under these conditions. In an accompanying paper, Grahammer et al suggest from 293 B inhibition of acid secretion that KCNQ1 is the K+ channel involved in K+ recycling at the apical membrane. Kir2.1 is not inhibited by 293B. Acid accumulation by H+/K+ ATPase-containing vesicles from stimulated rabbits is insensitive to 293B. This finding strongly suggests that KCNQ1 is not involved in K+ recycling at the apical membrane of the gastric parietal cell. Kir2.1 is a candidate for this process.
KeywordsAcid Secretion Apical Membrane Parietal Cell Acid Accumulation Proton Transport
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- 2.Cuppoletti J, Tewari KP, Sherry AM, Kupert EY, and Malinowska DH. ClC-2 Cl- channels in human lung epithelia: activation by arachidonic acid, amidation, and acid-activated omeprazole. Am J Physiol Cell Physiol 281: C46–54, 2001.Google Scholar
- 4.Cuppoletti J, Baker AM, and Malinowska DH. Acidophilic Cl- and K+ channels of the gastric parietal cell: a new model of regulated acid secretion. In: NATO ASI Cell Biology Series H89: Molecular and Cellular Mechanisms of H+ Transport, edited by Hirst BH. Springer-Verlag, 1994, p. 383–390. (Proc. NATO Advanced Research Workshop, 1994)Google Scholar
- 5.Cuppoletti J, Baker AM, and Malinowska DH. Cl- channels of the gastric parietal cell that are active at low pH. Am J Physiol Cell Physiol 264: C1609–C1618, 1993.Google Scholar
- 8.Grahammer F, Herling AW, Lang HJ, Schmitt-Grass A, Wittekindt OH, Nitschke R, Bleich M, Barhanin J, and Warth R. Identification of potaassium channels associated with H+/K+-ATPase in the parietal cell. Proceedings of the 9th International Proton Transport Conference “Mechanisms and Consequences of Proton Transport”, p. 92–93, 2001.Google Scholar
- 9.Horio Y, Mouri T, Fujita A, Inanobe A, Tanemoto M, and Kurachi Y. Inward rectifying K+ channel Kir4.1 participates in gastric acid secretion. Physiologist 42: A-18, Abstract 10.14, 1999.Google Scholar
- 11.Malinowska DH, Kupert EY, Sherry AM, and Cuppoletti J. A candidate K+ channel involved in gastric HCl secretion. Experimental Biology Meeting, San Diego, CA (April 2000). FASEB J 14: A338, Abstract #275.4, 2000.Google Scholar
- 12.Malinowska DH, Kupert EY, Bahinski A, Sherry AM, and Cuppoletti J. Cloning, functional expression, and characterization of a PKA-activated gastric Cl- channel. Am J Physiol Cell Physiol 268: C191–C200, 1995.Google Scholar
- 13.Reenstra WW and Forte JG. Characterization of K+ and Cl- conductances in apical membrane vesicles from stimulated rabbit oxyntic cells. Am J Physiol Gastrointest Liver Physiol 259: G850–G858, 1990.Google Scholar
- 14.Saccomani G, Psarras CG, Smith PR, Kirk KL, and Shoemaker RL. Histamine-induced chloride channels in apical membrane of isolated rabbit parietal cells. Am J Physiol Cell Physiol 260: C1000–1011, 1991.Google Scholar
- 16.Tewari KP, Malinowska DH, Sherry AM, and Cuppoletti J. PKA and arachidonic acid activation of human recombinant ClC-2 chloride channels. Am J Physiol Cell Physiol 279: C40–50, 2001.Google Scholar
- 18.Wolosin JM and Forte JG. Stimulation of oxyntic cell triggers K+ and Cl- conductances in apical H+-K+-ATPase membrane. Am J Physiol Cell Physiol 246: C537–C545, 1984.Google Scholar