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 simultaneously, we used Xenopus 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 microA). During hyperpolarizing pulses, the permeability for ATP(4-) was more than 4000 times higher than that for Cl(-). The sensitivity to GdCl(3) (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.
Bodas
E
E
Laboratory of Molecular Neurobiology, Department of Cell Biology and Pathology, Medical School, Hospital of Bellvitge, University of Barcelona, Campus of Bellvitge, Feixa Llarga s/n, L'Hospitalet de Llobregat, E-08907 Barcelona, Spain.
Aleu
J
J
Pujol
G
G
Martin-Satué
M
M
Marsal
J
J
Solsona
C
C
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism; D001081:Apyrase; D002462:Cell Membrane / Q000378:metabolism*; D002463:Cell Membrane Permeability; D003486:Cyanides / Q000494:pharmacology; D006801:Humans; D007473:Ion Channels / Q000378:metabolism*; D009865:Oocytes / Q000201:enzymology / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D014176:Protein Biosynthesis; D014981:Xenopus
D015703:Antigens, CD; D003486:Cyanides; D007473:Ion Channels; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; C027201:ectoATPase; D001081:Apyrase; C067869:CD39 antigen