VOLTAGE-DEPENDENT SODIUM AND POTASSIUM CURRENTS IN CULTURED TROUT ASTROCYTES

Autor(en): GLASSMEIER, G
JESERICH, G
KRUPPEL, T
Stichwörter: BONY FISH; CHANNEL EXPRESSION; ELECTROPHYSIOLOGY; GATED SODIUM; GLIAL-CELLS; HIPPOCAMPAL ASTROCYTES; INVITRO; ION CHANNELS; NA+; NEUROGLIA; Neurosciences; Neurosciences & Neurology; OPTIC-NERVE; SCHWANN-CELLS; WHITE MATTER
Erscheinungsdatum: 1994
Herausgeber: WILEY
Journal: GLIA
Volumen: 11
Ausgabe: 3
Startseite: 245
Seitenende: 254
Zusammenfassung: 
Voltage-gated ionic currents were recorded from cultured trout astrocytes with the whole-cell variation of the patch-clamp technique. In a subpopulation of astrocytes depolarizations above -40 mV activated a fast transient inward current that was identified as a sodium current by ion substitution experiments, its current reversal potential, and its TTX-sensitivity. Regarding threshold of activation, peak current voltage, and amplitude this current closely resembled those previously described for mammalian astrocytes. Voltage-dependence of inactivation and kinetics, however, markedly differed from the `'glial-like'' sodium current occurring in mammalian hippocampal or optic nerve astrocytes, since the sodium current of trout astrocytes exhibited a faster time course of activation and decay and a more depolarized steady-state inactivation curve with midpoints close to -60 mV. During a period of 2 weeks in culture the biophysical properties of the sodium current did not change significantly, albeit a continuous decrease in current density was observed. At depolarizing voltage steps positive to -40 mV, additionally voltage-gated potassium outward currents were evoked, which could be separated into a steady-state current with delayed rectifier properties and an inactivating component resembling the A-type current. Moreover, in a subpopulation of astrocytes an inward potassium current was elicited at hyperpolarizing potentials, which exhibited biophysical features consistent with the potassium inward rectifier of mammalian astrocytes. (C) 1994 Wiley-Liss, Inc.
ISSN: 08941491
DOI: 10.1002/glia.440110305

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