Anoxic depolarization of hippocampal astrocytes: Possible modulation by P2X7 receptors |
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Authors: | Anna Leichsenring Thomas RiedelYing Qin Patrizia RubiniPeter Illes |
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Affiliation: | Rudolf-Boehm-Institute of Pharmacology and Toxicology, University of Leipzig, D-04107 Leipzig, Germany |
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Abstract: | Current responses from CA1 neurons and stratum oriens astrocytes were recorded from hippocampal brain slices by means of the whole-cell patch-clamp technique. Anoxic depolarization (AD) was induced by an oxygen/glucose-deprived (OGD) medium also containing sodium iodoacetate and antimycin, in order to block glycolysis and oxidative phosphorylation, respectively. Anoxic depolarization has been reported to be due to the sudden increase of the extracellular K+ concentration and the accompanying explosive rise in glutamate concentration. We asked ourselves whether the release of ATP activating P2X7 receptors is also involved in the AD. Although, the AD was evoked in absolute synchrony in neurons and astrocytes, and the NMDA receptor antagonistic AP-5 depressed these responses, neither the non-selective P2 receptor antagonist PPADS, nor the highly selective P2X7 receptor antagonist A438079 interfered with the AD or its delay time in neurons/astrocytes after inducing chemical hypoxia. However, A438079, but not PPADS increased in astrocytes the slow inward current observed in a hypoxic medium. It is concluded that ATP co-released with glutamate by hypoxic stimulation has only a minor function in the present brain slice system. |
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Keywords: | AD, anoxic depolarization BzATP, dibenzoyl-ATP Cm, membrane capacitance CNS, central nervous system OGD, oxygen/glucose-deprivation Rm, membrane resistance TTX, tetrodotoxin Vm, membrane potential X2+, divalent cation |
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