Gruetter R, Seaquist E R, Kim S, Ugurbil K
Departments of Radiology, Medicine, Psychiatry and Biochemistry, University of Minnesota, Minneapolis, Minn., USA.
Dev Neurosci. 1998;20(4-5):380-8. doi: 10.1159/000017334.
Using optimized administration of 13C-labeled glucose, the time course of the specific activity of glucose was measured directly by in vivo 13C-NMR in the human brain at 4 Tesla. Subsequent label incorporation was measured at the C2, C3 and C4 positions of both glutamate and the well-resolved C2, C3 and C4 resonances of glutamine and at the C2 and C3 positions of aspartate. GABA was clearly observed for the first time in vivo, suggesting a substantial GABA turnover in the normal human visual cortex. Likewise, lactate C3 labeled with an estimated active pool size on the order of 0.5 mM. A model of cerebral glutamate metabolism is proposed which predicts that glutamatergic action ('neurotransmission'), pyruvate carboxylase flux, TCA cycle activity, glucose consumption and exchange across the mitochondrial membrane can be assessed simultaneously in the human brain.
通过优化13C标记葡萄糖的给药方式，在4特斯拉磁场下，利用体内13C核磁共振直接测量了人脑中葡萄糖比活度的时间进程。随后，在谷氨酸的C2、C3和C4位置以及谷氨酰胺分辨率良好的C2、C3和C4共振峰处，以及天冬氨酸的C2和C3位置测量了标记物的掺入情况。首次在体内清晰观察到γ-氨基丁酸（GABA），这表明正常人视觉皮层中存在大量的GABA周转。同样，乳酸C3的标记显示其活性池大小估计约为0.5 mM。提出了一种脑谷氨酸代谢模型，该模型预测，在人脑中可以同时评估谷氨酸能作用（“神经传递”）、丙酮酸羧化酶通量、三羧酸循环活性、葡萄糖消耗以及线粒体膜的交换情况。
