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Acetylcholine-activated chloride current in the T-84 colonic cell line
W H Cliff1, M E Duffey, N Packianathan
1Department of Biology, Niagara University, Niagara University, NY 14109, USA.
Pflugers Archiv : European Journal of Physiology
|June 20, 1998
Summary
Acetylcholine stimulates epithelial chloride secretion by activating very low conductance chloride channels in T-84 cells. This study used patch-clamp to investigate these channels, revealing their sensitivity to calcium and G proteins.
Area of Science:
- Cell biology
- Ion channel physiology
- Gastrointestinal physiology
Background:
- Hormones and neurotransmitters regulate epithelial chloride secretion via apical membrane chloride channels.
- Understanding the specific channels involved in cholinergic signaling is crucial for comprehending colonic fluid balance.
Purpose of the Study:
- To investigate the regulation of chloride current by acetylcholine in T-84 colonic cells.
- To characterize the properties of the chloride channels activated by cholinergic stimulation.
Main Methods:
- Single-channel patch-clamp electrophysiology was employed on T-84 colonic cell lines.
- Cells were treated with carbachol and AlF4- to assess chloride current responses.
- Excised patches were used to determine calcium sensitivity and channel kinetics.
Main Results:
- Carbachol stimulated transient chloride currents in a significant portion of patches.
- Single-channel conductance was determined to be less than 5 pS.
- Chloride currents were sensitive to free Ca2+ concentrations and showed time-dependent gating.
Conclusions:
- Cholinergic activation of chloride conductance in T-84 cells involves very low conductance chloride channels.
- G proteins and calcium ions play roles in the regulation of these channels.
- These findings contribute to understanding epithelial ion transport mechanisms.