A One‐Dimensional (Proton and Phosphorus) and Two‐Dimensional (Proton) In Vivo NMR Spectroscopic Study of Reversible Global Cerebral Ischemia

: The suitability of two‐dimensional (2D) proton spectroscopy for monitoring, in vivo, the changes in levels of brain metabolites induced by cerebral ischemia was investigated in an experimental model of 30‐min reversible ischemia induced by four‐vessel occlusion in the rat. The resulting data were compared with those obtained by one‐dimensional (1D) proton and phosphorus spectroscopy. Phosphorus spectra obtained during ischemia showed significant drops in levels of phosphocreatine (−73%), β‐ATP (−60%), and intracellular pH (to 6.30) and an increase in inorganic phosphate level (905%). 1D and 2D proton spectra showed decreases in the N‐acetylaspartate/creatine‐phosphocreatine ratio that were not significantly different [−21% (1D) and −32% (2D)]. Similarly, the increases in lactate/creatine‐phosphocreatine ratio were not significantly different [2,546% (1D) and 3,020% (2D)]. 2D spectroscopy also indicated a decrease in aspartate (−66%) and an increase in the inositol‐choline derivative (+124%) pools during ischemia and an increase in alanine pool (+516%) during reperfusion. The glutamate‐glutamine pool and taurine content did not change significantly during ischemia but decreased during reperfusion. The glucose level transiently decreased (−67%) during ischemia and increased immediately after (+261%). The levels of all the metabolites investigated returned to control values within 175 min after ischemia. 2D spectroscopy seems to be a reliable method of monitoring the changes in levels of cerebral compounds known to be involved in ischemia.