Mangia Silvia, Tkác Ivan, Gruetter Rolf, Van de Moortele Pierre-Francois, Maraviglia Bruno, Uğurbil Kâmil
Department of Radiology, Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota 55455, USA.
J Cereb Blood Flow Metab. 2007 May;27(5):1055-63. doi: 10.1038/sj.jcbfm.9600401. Epub 2006 Oct 11.
To date, functional 1H NMR spectroscopy has been utilized to report the time courses of few metabolites, primarily lactate. Benefiting from the sensitivity offered by ultra-high magnetic field (7 T), the concentrations of 17 metabolites were measured in the human visual cortex during two paradigms of visual stimulation lasting 5.3 and 10.6 mins. Significant concentration changes of approximately 0.2 micromol/g were observed for several metabolites: lactate increased by 23%+/-5% (P<0.0005), glutamate increased by 3%+/-1% (P<0.01), whereas aspartate decreased by 15%+/-6% (P<0.05). Glucose concentration also manifested a tendency to decrease during activation periods. The lactate concentration reached the new steady-state level within the first minute of activation and came back to baseline only after the stimulus ended. The changes of the concentration of metabolites implied a rise in oxidative metabolism to a new steady-state level during activation and indicated that amino-acid homeostasis is affected by physiological stimulation, likely because of an increased flux through the malate-aspartate shuttle.
迄今为止，功能1H核磁共振波谱已被用于报告少数代谢物的时间进程，主要是乳酸。受益于超高磁场（7T）提供的灵敏度，在持续5.3分钟和10.6分钟的两种视觉刺激范式期间，测量了人类视觉皮层中17种代谢物的浓度。观察到几种代谢物的浓度有显著变化，约为0.2微摩尔/克：乳酸增加了23%±5%（P<0.0005），谷氨酸增加了3%±1%（P<0.01），而天冬氨酸减少了15%±6%（P<0.05）。葡萄糖浓度在激活期也呈现出下降趋势。乳酸浓度在激活的第一分钟内达到新的稳态水平，并且仅在刺激结束后才恢复到基线。代谢物浓度的变化表明在激活期间氧化代谢上升到一个新的稳态水平，并表明氨基酸稳态受到生理刺激的影响，这可能是由于通过苹果酸-天冬氨酸穿梭的通量增加所致。
