Cellular chloride depletion inhibits cAMP-activated electrogenic chloride fluxes in HT29-18-C1 cells
| Autor: | Marshall H. Montrose, C. F. Lo, D. L. Blackmon, D. M. Fine, L. Aguillar |
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| Rok vydání: | 1995 |
| Předmět: |
Anions
Intracellular Fluid Cell Membrane Permeability Sodium-Potassium-Chloride Symporters Physiology Potassium Inorganic chemistry Biophysics Cystic Fibrosis Transmembrane Conductance Regulator chemistry.chemical_element Gluconates Chloride chemistry.chemical_compound Valinomycin Chlorides Chloride Channels Furosemide Cations Cyclic AMP Tumor Cells Cultured medicine Humans Intestinal Mucosa Bumetanide Cell Size Nitrates Forskolin Ionomycin Quinolinium Compounds Colforsin Cell Polarity Biological Transport Cell Biology Apical membrane Electrophysiology chemistry Organ Specificity Osmolyte Cell culture Colonic Neoplasms Carrier Proteins Intracellular medicine.drug |
| Zdroj: | The Journal of Membrane Biology. 145 |
| ISSN: | 1432-1424 0022-2631 |
| Popis: | Cyclic AMP-activated chloride fluxes have been analyzed in HT29-18-C1 cells (a clonal cell line derived from a human colon carcinoma) using measurements of cell volume (electronic cell sizing), cell chloride content (chloride titrator) and intracellular chloride activity (6-methoxy-N-(3-sulfopropyl)quinolinium; SPQ). HT29-18-C1 was shown to mediate polarized chloride transport. In unstimulated cells, the apical membrane was impermeable to chloride and net chloride flux was mediated by basolateral furosemide-sensitive transport. Forskolin (10) (μm) increased furosemideinsensitive chloride permeability of the apical membrane, and decreased steady-state intracellular chloride concentration approximately 9%. Cellular chloride depletion (substitution of medium chloride by nitrate or gluconate), caused greater than fourfold reduction in cellular chloride concentration. When chloride-depleted cells were returned to normal medium, cells regained chloride and osmolytes via bumetanide-sensitive transport, but forskolin did not stimulate bumetanideinsensitive chloride uptake. The inhibition of cAMP-activated chloride reuptake was not explained by limiting cation conductance, cell shrinkage, choice of substitute anion, or decreased generation of cAMP in chloridedepleted cells. When cells with normal chloride content were depolarized (135 mm medium potassium + 10 μm valinomycin), cAMP activated electrogenic chloride uptake permselective for Cl−≈Br−>NO 3 − >I−. The electrogenic transport pathway was inhibited in chloridedepleted cells. Results suggest that chloride depletion limits activation of electrogenic chloride flux. |
| Databáze: | OpenAIRE |
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