Abstract
In liver cells, cation-selective channels are permeable to Ca2+ and have been postulated to represent a pathway for receptor-mediated Ca2+ influx. This study examines the mechanisms involved in the regulation of these channels in a model liver cell line. Using patch-clamp recording techniques, it is shown that channel open probability is a saturable function of cytosolic [Ca2+], with half-maximal opening at 660 nM. By contrast, channel opening is not affected by membrane voltage or cytosolic pH. In intact cells, reduction of cytosolic [Cl-], a physiological response to Ca2+-mobilizing hormones and cell swelling, is also associated with an increase in channel opening. Finally, channel opening is inhibited by intracellular ATP through a mechanism that does not involve ATP hydrolysis. These findings suggest that opening of cation-selective channels is coupled to the metabolic state of the cell and provides a positive feedback mechanism for regulation of receptor-mediated Na+ and Ca2+ influx.
Original language | English (US) |
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Pages (from-to) | 231-236 |
Number of pages | 6 |
Journal | Journal of Membrane Biology |
Volume | 157 |
Issue number | 3 |
DOIs | |
State | Published - 1997 |
Keywords
- Calcium
- Hepatocytes
- Nonselective cation channels
- Patch clamp
- Signaling
ASJC Scopus subject areas
- Biophysics
- Physiology
- Cell Biology