Publications [#132804] of G. Allan Johnson
- H Benveniste, LW Hedlund, GA Johnson, Mechanism of detection of acute cerebral ischemia in rats by diffusion-weighted magnetic resonance microscopy.,
Stroke; a journal of cerebral circulation, UNITED STATES, vol. 23 no. 5
pp. 746-54, ISSN 0039-2499
(last updated on 2005/08/03)
BACKGROUND AND PURPOSE: The aim of this study was to measure apparent diffusion coefficients in rat brain tissue exposed to ouabain, glutamate, and N-methyl-D-aspartate and to compare them with apparent diffusion coefficients found in acute cerebral ischemia. METHODS: The apparent diffusion coefficient was measured using magnetic resonance microscopy in four groups of Sprague-Dawley rats after occlusion of the right middle cerebral artery and ipsilateral common carotid artery (n = 7), after ouabain exposure (n = 6), during glutamate exposure (n = 7), or during N-methyl-D-aspartate exposure (n = 3). Ouabain, glutamate, and N-methyl-D-aspartate were applied via an intracerebrally implanted microdialysis membrane. RESULTS: Three hours after the induction of focal cerebral ischemia, a 33% reduction in the apparent diffusion coefficient was observed in the right dorsolateral corpus striatum and olfactory cortex. After ouabain exposure, reductions in the apparent diffusion coefficient were observed within a 1,500-microns radius of the microdialysis membrane. Quantitative analysis revealed that apparent diffusion coefficient values in ischemic and ouabain-exposed tissue fell within the same range. Glutamate and N-methyl-D-aspartate reduced the brain tissue apparent diffusion coefficient by 35% and 40%, respectively. CONCLUSIONS: On the basis of these findings, we conclude that ischemia-induced apparent diffusion coefficient reductions are likely caused by a shift of extracellular to intracellular water.
Acute Disease • Animals • Brain • Brain Ischemia • Diffusion • Female • Glutamates • Glutamic Acid • Magnetic Resonance Imaging • N-Methylaspartate • Ouabain • Rats • Rats, Inbred Strains • Staining and Labeling • diagnosis* • drug effects • metabolism • methods* • pharmacology