Abstract
ATP plays an important role in signal transduction between neuronal and glial circuits and within glial networks. Here we describe currents activated by ATP in astrocytes acutely isolated from cortical brain slices by non-enzymatic mechanical dissociation. Brain slices were prepared from transgenic mice that express enhanced green fluorescent protein under the control of the human glial fibrillary acidic protein promoter. Astrocytes were studied by whole-cell voltage clamp. Exogenous ATP evoked inward currents in 75 of 81 astrocytes. In the majority ( approximately 65%) of cells, ATP-induced responses comprising a fast and delayed component; in the remaining subpopulation of astrocytes, ATP triggered a smoother response with rapid peak and slowly decaying plateau phase. The fast component of the response was sensitive to low concentrations of ATP (with EC(50) of approximately 40 nm). All ATP-induced currents were blocked by pyridoxal-phosphate-6-azophenyl-2',4'-disulfonate (PPADS); they were insensitive to ivermectin. Quantitative real-time PCR demonstrated strong expression of P2X(1) and P2X(5) receptor subunits and some expression of P2X(2) subunit mRNAs. The main properties of the ATP-induced response in cortical astrocytes (high sensitivity to ATP, biphasic kinetics, and sensitivity to PPADS) were very similar to those reported for P2X(1/5) heteromeric receptors studied previously in heterologous expression systems.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Adenosine Triphosphate / analogs & derivatives
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Adenosine Triphosphate / pharmacology
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Animals
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Animals, Newborn
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Astrocytes / drug effects
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Astrocytes / metabolism*
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Calcium / metabolism
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Cerebral Cortex / cytology*
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Dose-Response Relationship, Drug
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Dose-Response Relationship, Radiation
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Flow Cytometry / methods
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Glial Fibrillary Acidic Protein / biosynthesis
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Glial Fibrillary Acidic Protein / genetics
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Green Fluorescent Proteins / biosynthesis
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Green Fluorescent Proteins / genetics
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Humans
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Membrane Potentials / drug effects
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Membrane Potentials / physiology
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Membrane Potentials / radiation effects
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Mice
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Mice, Transgenic
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Patch-Clamp Techniques / methods
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Platelet Aggregation Inhibitors / pharmacology
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Pyridoxal Phosphate / analogs & derivatives
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Pyridoxal Phosphate / pharmacology
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Receptors, Purinergic P2 / metabolism*
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Receptors, Purinergic P2 / physiology*
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Receptors, Purinergic P2X
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Receptors, Purinergic P2X2
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Receptors, Purinergic P2X5
Substances
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Glial Fibrillary Acidic Protein
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P2RX2 protein, human
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P2RX5 protein, human
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P2rx2 protein, mouse
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P2rx5 protein, mouse
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Platelet Aggregation Inhibitors
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Receptors, Purinergic P2
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Receptors, Purinergic P2X
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Receptors, Purinergic P2X2
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Receptors, Purinergic P2X5
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Green Fluorescent Proteins
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pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid
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Pyridoxal Phosphate
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2',3'-O-(2,4,6-trinitro-cyclohexadienylidine)adenosine 5'-triphosphate
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Adenosine Triphosphate
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Calcium