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- Title
Proton transfer ratio, lactate, and intracellular pH in acute cerebral ischemia.
- Authors
Jokivarsi, Kimmo T.; Gröhn, Heidi I.; Gröhn, Olli H.; Kauppinen, Risto A.
- Abstract
The amide proton transfer ratio (APTR) from the asymmetry of the Z-spectrum was determined in rat brain tissue during and after unilateral middle cerebral artery occlusion (MCAo). Cerebral lactate (Lac) as determined by 1H NMR spectroscopy, water diffusion, and T1ρ were quantified as well. Lac concentrations were used to estimate intracellular pH (pHi) in the brain during the MCA occlusion. A decrease in APTR during occlusion indicated acidification from 7.1 to 6.79 ± 0.19 (a drop by 0.3 ± 0.2 pH units), whereas pHi computed from Lac concentration was 6.3 ± 0.2 (a drop by 0.8 ± 0.2 pH units). Despite the disagreement between the two methods in terms of the size of the change in the absolute pHi during ischemia, ΔAPTR and pHi (and Lac concentration) displayed a strong correlation during the MCAo. Diffusion and T1ρ indicated cytotoxic edema following MCA occlusion; however, APTR returned slowly toward the values determined in the contralateral hemisphere post-ischemia. These data argue that the APTR during ischemia is affected not only by pHi but by other physicochemical factors as well, and indicates different aspects of pathology in the post-ischemic brain compared to those that influence water diffusion and T1ρ. Magn Reson Med 57:647-653, 2007. © 2007 Wiley-Liss, Inc.
- Publication
Magnetic Resonance in Medicine, 2007, Vol 57, Issue 4, p647
- ISSN
0740-3194
- Publication type
Article
- DOI
10.1002/mrm.21181