| Autor: |
Sager, Thomas Nikolaj, Laursen, Henning, Fink-Jensen, Anders, Topp, Simon, Stensgaard, Anders, Hedehus, Maj, Rosenbaum, Sverre, Valsborg, Jacob Stenmann, Hansen, Anker Jon |
| Zdroj: |
Journal of Cerebral Blood Flow and Metabolism; February 1999, Vol. 19 Issue: 2 p164-172, 9p |
| Abstrakt: |
Brain N-acetylaspartate (NAA) can be quantified by in vivoproton magnetic resonance spectroscopy (1H-MRS) and is used in clinical settings as a marker of neuronal density. It is, however, uncertain whether the change in brain NAA content in acute stroke is reliably measured by 1H-MRS and how NAA is distributed within the ischemic area. Rats were exposed to middle cerebral artery occlusion. Preischemic values of [NAA] in striatum were 11 mmol/L by 1H-MRS and 8 mmol/kg by HPLC. The methods showed a comparable reduction during the 8 hours of ischemia. The interstitial level of [NAA] ([NAA]e) was determined by microdialysis using [3H]NAA to assess in vivorecovery. After induction of ischemia, [NAA]eincreased linearly from 70 µmol/L to a peak level of 2 mmol/L after 2 to 3 hours before declining to 0.7 mmol/L at 7 hours. For comparison, [NAA]ewas measured in striatum during global ischemia, revealing that [NAA]eincreased linearly to 4 mmol/L after 3 hours and this level was maintained for the next 4 h. From the change in in vivorecovery of the interstitial space volume marker [14C]mannitol, the relative amount of NAA distributed in the interstitial space was calculated to be 0.2% of the total brain NAA during normal conditions and only 2 to 6% during ischemia. It was concluded that the majority of brain NAA is intracellularly located during ischemia despite large increases of interstitial [NAA]. Thus, MR quantification of NAA during acute ischemia reflects primarily changes in intracellular levels of NAA. |
| Databáze: |
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