ATP Crossing the Cell Plasma Membrane Generates an Ionic Current in Xenopus Oocytes

The presence of ATP within cells is well established. However, ATP also operates as an intercellular signal via specific purinoceptors. Furthermore, nonsecretory cells can release ATP under certain experimental conditions. To measure ATP release and membrane currents from a single cell simultaneousl...

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Published in:The Journal of biological chemistry 2000-07, Vol.275 (27), p.20268-20273
Main Authors: Bodas, Elena, Aleu, Jordi, Pujol, Gemma, Martı́n-Satué, Mireia, Marsal, Jordi, Solsona, Carles
Format: Article
Language:English
Subjects:
Adenosine Triphosphatases - genetics
Adenosine Triphosphatases - metabolism
Adenosine Triphosphate - metabolism
Adenosine Triphosphate - pharmacology
Animals
Antigens, CD - genetics
Antigens, CD - metabolism
Apyrase
Cell Membrane - metabolism
Cell Membrane Permeability
Cyanides - pharmacology
Humans
Ion Channels - metabolism
Oocytes - enzymology
Oocytes - metabolism
Patch-Clamp Techniques
Protein Biosynthesis
Xenopus
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Summary:The presence of ATP within cells is well established. However, ATP also operates as an intercellular signal via specific purinoceptors. Furthermore, nonsecretory cells can release ATP under certain experimental conditions. To measure ATP release and membrane currents from a single cell simultaneously, we usedXenopus oocytes. We simultaneously recorded membrane currents and luminescence. Here, we show that ATP release can be triggered in Xenopus oocytes by hyperpolarizing pulses. ATP release (3.2 ± 0.3 pmol/oocyte) generated a slow inward current (2.3 ± 0.1 μA). During hyperpolarizing pulses, the permeability for ATP4– was more than 4000 times higher than that for Cl–. The sensitivity to GdCl3 (0.2 mm) of hyperpolarization-induced ionic current, ATP release and E-ATPase activity suggests their dependence on stretch-activated ion channels. The pharmacological profile of the current inhibition coincides with the inhibition of ecto-ATPase activity. This enzyme is highly conserved among species, and in humans, it has been cloned and characterized as CD39. The translation, in Xenopus oocytes, of human CD39 mRNA encoding enhances the ATP-supported current, indicating that CD39 is directly or indirectly responsible for the electrodiffusion of ATP.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M000894200