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ATP-activated cation currents in single guinea-pig hepatocytes
1INSERM U442, Bâtiment 443, Universite Paris-Sud, 91405 Orsay Cedex, France. thierry.capiod@ibaic.u-psud.fr
The Journal of Physiology
|May 23, 1998
Summary
This study shows that external adenosine triphosphate (ATP) activates cation channels in guinea-pig liver cells, leading to inward currents. These channels are permeable to various divalent cations and desensitize over time.
Area of Science:
- Cellular physiology
- Ion channel function
Background:
- Adenosine triphosphate (ATP) acts as an extracellular signaling molecule.
- Purinergic receptors, including P2X and P2Y, mediate cellular responses to ATP.
Purpose of the Study:
- To investigate the electrophysiological responses of single guinea-pig liver cells to external ATP.
- To characterize the properties of ATP-activated ion channels in these cells.
Main Methods:
- Whole-cell voltage clamp technique applied to isolated guinea-pig liver cells.
- Application of varying concentrations of ATP and different cations to assess current responses.
- Measurement of ion flux and desensitization kinetics.
Main Results:
- ATP application elicited a large, cation-selective inward current at negative holding potentials.
- The ATP-activated conductance was permeable to divalent cations like Ca2+, Cd2+, Ni2+, Mn2+, and Mg2+.
- The current response desensitized in the continuous presence of ATP, with varying time constants depending on the cation composition.
Conclusions:
- Single guinea-pig liver cells possess ATP-activated cation channels, likely P2X receptors.
- These channels exhibit permeability to multiple divalent cations and undergo desensitization.
- ATP-induced Ca2+ influx may influence intracellular calcium dynamics and purinoceptor signaling pathways.