Henry Pierre-Gilles, Tkác Ivan, Gruetter Rolf
Department of Radiology, Center for Magnetic Resonance Research, University of Minnesota Medical School, Minneapolis Minnesota.
Magn Reson Med. 2003 Oct;50(4):684-92. doi: 10.1002/mrm.10601.
Localized (13)C NMR spectra were obtained from the rat brain in vivo over a broad spectral range (15-100 ppm) with minimal chemical-shift displacement error (<10%) using semi-adiabatic distortionless enhancement by polarization transfer (DEPT) combined with (1)H localization. A new gradient dephasing scheme was employed to eliminate unwanted coherences generated by DEPT when using surface coils with highly inhomogeneous B(1) fields. Excellent sensitivity was evident from the simultaneous detection of natural abundance signals for N-acetylaspartate, myo-inositol, and glutamate in the rat brain in vivo at 9.4 T. After infusion of (13)C-labeled glucose, up to 18 (13)C resonances were simultaneously measured in the rat brain, including glutamate C2, C3, C4, glutamine C2, C3, C4, aspartate C2, C3, glucose C1, C6, N-acetyl-aspartate C2, C3, C6, as well as GABA C2, lactate C3, and alanine C3. (13)C-(13)C multiplets corresponding to multiply labeled compounds were clearly observed, suggesting that extensive isotopomer analysis is possible in vivo. This unprecedented amount of information will be useful for metabolic modeling studies aimed at understanding brain energy metabolism and neurotransmission in the rodent brain.
使用极化转移（DEPT）结合¹H定位的半绝热无失真增强技术，在大鼠脑内体内获得了局部（¹³C）核磁共振谱，谱范围宽（15 - 100 ppm），化学位移误差最小（<10%）。当使用具有高度不均匀B₁场的表面线圈时，采用了一种新的梯度去相方案来消除DEPT产生的不需要的相干性。在9.4 T下对大鼠脑内体内的N - 乙酰天门冬氨酸、肌醇和谷氨酸的自然丰度信号进行同时检测，灵敏度极佳。注入¹³C标记的葡萄糖后，在大鼠脑中同时测量到多达18个¹³C共振峰，包括谷氨酸C2、C3、C4，谷氨酰胺C2、C3、C4，天冬氨酸C2、C3，葡萄糖C1、C6，N - 乙酰天门冬氨酸C2、C3、C6，以及GABA C2、乳酸C3和丙氨酸C3。清晰观察到对应多重标记化合物的¹³C - ¹³C多重峰，表明体内广泛的同位素异构体分析是可行的。这一前所未有的信息量将有助于旨在理解啮齿动物脑内能量代谢和神经传递的代谢建模研究。
