Activity-Dependent Plasticity of Astroglial Potassium and Glutamate Clearance

Figure 1

Pharmacological isolation of astroglial currents. Dual patch clamp recordings revealed synaptically evoked astroglial currents in hippocampal CA1 region. Sample traces are shown for simultaneously recorded (a) neuronal field excitatory postsynaptic potentials (fEPSPs) and (b) astroglial currents induced by a single stimulation of Schaffer collaterals. This was carried out under control conditions (100 μM picrotoxin; 1), and subsequent addition of an ionotropic glutamate receptor antagonist (5 mM kynurenic acid; 2), and a glutamate transporter antagonist (200 μM TBOA; 3). (c) Sample traces of pharmacologically isolated astroglial currents are shown. Astrocytic potassium current was isolated by subtracting the kynurenic acid-insensitive component from the total current (, 1-2, blue). Note that the initial fast outward current component (dash blue) reflects fEPSPs generated by adjacent pyramidal cells, while corresponds to the slow inward current (solid blue). The kynurenic acid insensitive current (2) consists of a fast inward current and a slow residual component of smaller amplitude; the latter was isolated by subsequent application of TBOA (, 3, green). Subtraction of from the response in the presence of kynurenic acid resulted in the glutamate transporter current component (, 2-3, red). Scale bars = 0.1 mV for fEPSPs, 15 pA for astroglial currents; 25 ms. This figure (a–c) is extracted from [21].

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