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Chloride conductance in human atrial cells
R Sakai1, N Hagiwara, H Kasanuki
1Heart Institute of Japan, Tokyo Women's Medical College, Japan.
Journal of Molecular and Cellular Cardiology
|October 1, 1995
Summary
Cyclic AMP-dependent chloride current was not found in human atrial cells. However, swelling-induced chloride current was consistently observed, similar to findings in other cardiac cells.
Area of Science:
- Cardiology
- Ion Channels
- Cell Physiology
Background:
- Chloride current mechanisms in the human heart remain largely unknown.
- Previous studies have identified various chloride currents in animal cardiac cells.
Purpose of the Study:
- To investigate the presence and characteristics of cyclic AMP-dependent and swelling-induced chloride currents in human atrial cells.
- To clarify the role of chloride conductance in human cardiac physiology.
Main Methods:
- Isolated human atrial cells were studied using the whole-cell voltage-clamp technique.
- Cells were exposed to isoprenaline, forskolin, cyclic AMP, and hypotonic solutions to elicit specific currents.
- Chloride channel blockers were used to identify current characteristics.
Main Results:
- Isoprenaline significantly increased calcium current but did not activate cyclic AMP-dependent chloride current.
- Neither forskolin nor intracellular cyclic AMP induced a measurable cyclic AMP-dependent chloride current.
- Hypotonic superfusion induced outward rectifying current sensitive to chloride channel blockers, consistent with swelling-induced chloride current.
Conclusions:
- Cyclic AMP-dependent chloride current is not activated in human atrial cells under the tested conditions.
- A swelling-induced chloride current is present in human atrial cells and shares properties with currents found in other cardiac myocytes.