Gastric parietal cell secretory membrane contains PKA- and acid-activated Kir2.1 K+channels
| Autor: | John Cuppoletti, Kirti P. Tewari, Danuta H. Malinowska, Ann M. Sherry |
|---|---|
| Rok vydání: | 2004 |
| Předmět: |
Patch-Clamp Techniques
Physiology CHO Cells H(+)-K(+)-Exchanging ATPase Membrane Potentials Gastric Acid Xenopus laevis Parietal Cells Gastric Cricetinae medicine Animals Secretion RNA Messenger Cloning Molecular Potassium Channels Inwardly Rectifying Actin Ion transporter Parietal cell chemistry.chemical_classification Kir2.1 Membrane Proteins Epithelial Cells Cell Biology Hydrogen-Ion Concentration Cyclic AMP-Dependent Protein Kinases Cell biology medicine.anatomical_structure Enzyme Membrane chemistry Biochemistry Gastric Mucosa Oocytes Rabbits Ion Channel Gating |
| Zdroj: | American Journal of Physiology-Cell Physiology. 286:C495-C506 |
| ISSN: | 1522-1563 0363-6143 |
| DOI: | 10.1152/ajpcell.00386.2003 |
| Popis: | Our objective was to identify and localize a K+channel involved in gastric HCl secretion at the parietal cell secretory membrane and to characterize and compare the functional properties of native and recombinant gastric K+channels. RT-PCR showed that mRNA for Kir2.1 was abundant in rabbit gastric mucosa with lesser amounts of Kir4.1 and Kir7.1, relative to β-actin. Kir2.1 mRNA was localized to parietal cells of rabbit gastric glands by in situ RT-PCR. Resting and stimulated gastric vesicles contained Kir2.1 by Western blot analysis at ∼50 kDa as observed with in vitro translation. Immunoconfocal microscopy showed that Kir2.1 was present in parietal cells, where it colocalized with H+-K+-ATPase and ClC-2 Cl-channels. Function of native K+channels in rabbit resting and stimulated gastric mucosal vesicles was studied by reconstitution into planar lipid bilayers. Native gastric K+channels exhibited a linear current-voltage relationship and a single-channel slope conductance of ∼11 pS in 400 mM K2SO4. Channel open probability (Po) in stimulated vesicles was high, and that of resting vesicles was low. Reduction of extracellular pH plus PKA treatment increased resting channel Poto ∼0.5 as measured in stimulated vesicles. Full-length rabbit Kir2.1 was cloned. When stably expressed in Chinese hamster ovary (CHO) cells, it was activated by reduced extracellular pH and forskolin/IBMX with no effects observed in nontransfected CHO cells. Cation selectivity was K+= Rb+>> Na+= Cs+= Li+= NMDG+. These findings strongly suggest that the Kir2.1 K+channel may be involved in regulated gastric acid secretion at the parietal cell secretory membrane. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|