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Whole-cell membrane current and membrane resistance during hypoxic spreading depression
G Czéh1, P G Aitken, G G Somjen
1Department of Cell Biology, Duke University Medical Center, Durham, NC 27710.
Neuroreport
|February 1, 1992
Summary
Hypoxic spreading depression (SD) in rat hippocampus involves a significant inward current in CA1 pyramidal cells. This current, linked to reduced membrane resistance, is not fully explained by known voltage-dependent ion channels.
Area of Science:
- Neuroscience
- Cellular Electrophysiology
- Brain Physiology
Background:
- Spreading depression (SD) is a wave of intense neuronal activity followed by suppression.
- Understanding the ionic mechanisms of SD is crucial for neurological research.
Purpose of the Study:
- To investigate the membrane currents and resistance changes in CA1 pyramidal cells during hypoxic spreading depression (SD).
- To identify the ion channel mechanisms underlying SD-induced depolarization in the hippocampus.
Main Methods:
- Extracellular potential (Vo) and whole-cell patch clamp recordings were performed on rat hippocampal slices.
- CA1 pyramidal cells were studied during induced hypoxic spreading depression (SD).
- Ionic currents were analyzed with and without voltage-dependent K+ and Na+ channel blockers (Cs+ and QX-314).
Main Results:
- Hypoxic SD induced a sharp increase in holding current (Ih) and a significant decrease in membrane resistance (Rm) in CA1 pyramidal cells.
- The SD-related membrane current (ISD) reversed near 0 mV.
- Blocking voltage-dependent K+ and Na+ currents did not abolish the Ih shifts or Rm decrease during SD.
Conclusions:
- Hypoxic SD in CA1 pyramidal cells is associated with a substantial non-selective inward current.
- The underlying membrane mechanisms for this inward current remain unidentified.
- This current contributes to, but does not fully account for, the observed voltage shifts during SD.