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Interstitial volume changes during spreading depression (SD) and SD-like hypoxic depolarization in hippocampal tissue
J Jing1, P G Aitken, G G Somjen
1Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710.
Journal of Neurophysiology
|June 1, 1994
Summary
Interstitial volume dramatically decreases by about 70% during spreading depression (SD) and hypoxic SD-like depolarization (HSD). The remaining interstitial space (ISV) in the CA1 region during SD is less than 4% of total tissue volume.
Area of Science:
- Neuroscience
- Neurophysiology
- Brain Edema Research
Background:
- The interstitial volume (ISV) is crucial for understanding brain function and pathology.
- Changes in ISV are implicated in various neurological conditions, including spreading depression (SD).
Purpose of the Study:
- To quantify the relative interstitial volume (ISV) changes during spreading depression (SD) and hypoxic SD-like depolarization (HSD).
- To determine the extent of ISV reduction and its implications for ion movement in the brain.
Main Methods:
- Utilized iontophoretically administered tetramethylammonium (TMA+) and tetraethylammonium (TEA+) as probe ions.
- Induced spreading depression (SD) using high potassium (K+) and hypoxic SD-like depolarization (HSD) by oxygen withdrawal.
- Monitored probe ion concentration changes to estimate ISV.
Main Results:
- Probe ion concentrations increased significantly and similarly during both SD and HSD.
- Estimated a substantial average decrease in ISV by approximately 70% during these events.
- Observed that the patent ISV in the CA1 region during SD is less than 4% of total tissue volume.
Conclusions:
- Spreading depression and hypoxic SD-like depolarization cause a drastic reduction in interstitial volume.
- The limited ISV during SD suggests restricted extracellular space for ion diffusion.
- Hypoxic conditions may lead to transient probe ion passage through cell membranes.