Whole-cell membrane current and membrane resistance during hypoxic spreading depression.
In rat hippocampal tissue slices we recorded extracellular potential (Vo) and whole-cell patch clamp current of CA1 pyramid cells. During hypoxic spreading depression (SD)-like depolarization, the holding current (Ih) increased sharply. Membrane 'slope' resistance (Rm) decreased to 10-67% (mean 39%) of the resting value. The SD-related membrane current (ISD) reversed near zero mV. With voltage dependent K+ and Na+ currents blocked by Cs+ and QX-314, shifts of Ih and decrease of Rm during SD were not suppressed. We conclude that hypoxic SD of CA1 pyramidal cells is associated with a large non-selective inward current through yet to be identified membrane mechanisms, which cannot fully explain the SD-related Vo shift.
Czéh
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Department of Cell Biology, Duke University Medical Center, Durham, NC 27710.
Aitken
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Somjen
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D000818:Animals; D015687:Cell Hypoxia / Q000502:physiology*; D013181:Cortical Spreading Depression / Q000502:physiology*; D005260:Female; D006624:Hippocampus / Q000502:physiology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains