Intrinsic Optical Signals in Rat Hippocampal Slices During Hypoxia-Induced Spreading Depression-Like Depolarization

作者：Michael M. Müller, George G. Somjen · 发表于：Journal of Neurophysiology · 年份：1999 · DOI：10.1152/jn.1999.82.4.1818 · 被引用次数：99 · 研究领域：Neuroscience and Neuropharmacology Research、Photoreceptor and optogenetics research、Traumatic Brain Injury and Neurovascular Disturbances

In interfaced rat hippocampal slices spreading depression (SD) and hypoxia-induced SD-like depolarization are associated with increased light reflectance and decreased light transmittance, indicating increased light scattering. By contrast, mild hypotonicity or electrical stimulation decrease light scattering, which is usually taken to be caused by cell swelling. This difference has been attributed to experimental conditions, but in our laboratory moderate osmotic challenge and SD produced opposite intrinsic optical signals (IOSs) in the same slice under identical conditions. To decide whether the SD-induced IOS is related to cell swelling, we investigated the effects of Cl(-) transport inhibitors and Cl(-) withdrawal on both light reflectance and transmittance, as well as on changes in interstitial volume and tissue electrical resistance. In normal [Cl(-)](o), early during hypoxia, there was a slight decrease in light reflectance paired with increase in transmittance. At the onset of hypoxic SD, coincident with the onset of cell swelling (restriction of TMA(+) space), the IOS signals suddenly inverted, indicating sharply increased scattering. The SD-related IOSs started in a single spot and spread out over the entire CA1 region without invading CA3. Application of 2 mM furosemide decreased IOS intensity. When [Cl(-)](o) was substituted by methylsulfate or gluconate, the SD-related reflectance increase and transmittance decrease were suppressed and replaced by opposite signal...