Impaired K+ homeostasis and altered electrophysiological properties of post-traumatic hippocampal glia.

D’Ambrosio R., Maris D.O., Grady S.M., Winn H.R., and Janigro D. Journal of Neuroscience (1999), 19(18): 8152-62.

This work demonstrated that, two days after moderate traumatic brain injury, reactive glial cells have altered electrophysiology that results in the impairment of extracellular K+ homeostasis which in turn contributes to neuronal hyperexcitability.

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Complex glial cells have decreased KIR currents following fluid percussion injury. Complex cells in control hippocampal slices exhibited large Cs+-sensitive currents (A, top and bottom panel), and were characterized by a large Cs+-sensitive component (81±11% at –140mV, n=7). In contrast, complex cells in post-FPI hippocampal slices displayed little Cs+-sensitivity (B, top and bottom panel), and showed a decreased Cs+-sensitive component of the whole cell inward currents (28±8% at –140mV, n=7). C) The percentage of Cs+-sensitive currents (ICs) for complex cells in normal and post-FPI hippocampus is shown for membrane potentials from –140 to –80 mV. Voltage commands consisted of ramps from –170 to +100 mV over 750ms from holding potential of -70mV.