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High extracellular K+ evokes changes in voltage-dependent K+ and Na+ currents and volume regulation in astrocytes

  • Cellular Neurophysiology
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Abstract

[K+]e increase accompanies many pathological states in the CNS and evokes changes in astrocyte morphology and glial fibrillary acidic protein expression, leading to astrogliosis. Changes in the electrophysiological properties and volume regulation of astrocytes during the early stages of astrocytic activation were studied using the patch-clamp technique in spinal cords from 10-day-old rats after incubation in 50 mM K+. In complex astrocytes, incubation in high K+ caused depolarization, an input resistance increase, a decrease in membrane capacitance, and an increase in the current densities (CDs) of voltage-dependent K+ and Na+ currents. In passive astrocytes, the reversal potential shifted to more positive values and CDs decreased. No changes were observed in astrocyte precursors. Under hypotonic stress, astrocytes in spinal cords pre-exposed to high K+ revealed a decreased K+ accumulation around the cell membrane after a depolarizing prepulse, suggesting altered volume regulation. 3D confocal morphometry and the direct visualization of astrocytes in enhanced green fluorescent protein/glial fibrillary acidic protein mice showed a smaller degree of cell swelling in spinal cords pre-exposed to high K+ compared to controls. We conclude that exposure to high K+, an early event leading to astrogliosis, caused not only morphological changes in astrocytes but also changes in their membrane properties and cell volume regulation.

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Acknowledgements

This work was supported by grants 305/03/1172 and 305/06/1316 from the Grant Agency of the Czech Republic; AVOZ50390512, 1M0021620803, and LC554 from the Ministry of Education, Youth and Sports of the Czech Republic; and 57/2005/C/2.LF from the Grant Agency of Charles University, Prague. The authors would like to thank Dr. Ladislav Andera for help with GFAP quantification, Mgr. Petr Pivonka for developing a program for patch-clamp data analysis, and Hana Hronova for immunohistochemical staining.

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Author notes

  1. David Petrik

    Present address: Department of Physiology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229-3900, USA

Authors and Affiliations

  1. Department of Neurobiology, Institute of Experimental Medicine, The Academy of Sciences of the Czech Republic, Videnska 1083, Prague, 4-142 20, Czech Republic

    Helena Neprasova, Miroslava Anderova & Alexandr Chvatal

  2. Department of Neuroscience and Center for Cell Therapy and Tissue Repair, Second Medical Faculty, Charles University, V Uvalu 84, Prague, 5-150 06, Czech Republic

    Helena Neprasova, Miroslava Anderova, Lydia Vargova, Sarka Kubinova, Alexandr Chvatal & Eva Sykova

  3. Department of Neuroscience, Institute of Experimental Medicine, The Academy of Sciences of the Czech Republic, Videnska 1083, Prague, 4-142 20, Czech Republic

    Lydia Vargova, Sarka Kubinova & Eva Sykova

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  1. Helena Neprasova
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Correspondence to Miroslava Anderova.

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Neprasova, H., Anderova, M., Petrik, D. et al. High extracellular K+ evokes changes in voltage-dependent K+ and Na+ currents and volume regulation in astrocytes. Pflugers Arch - Eur J Physiol 453, 839–849 (2007). https://doi.org/10.1007/s00424-006-0151-9

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  • DOI: https://doi.org/10.1007/s00424-006-0151-9

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