• Ibrahim Jalloh, Adel Helmy, Duncan J Howe, Richard J Shannon, Peter Grice, Andrew Mason, Clare N Gallagher, Michael P Murphy, John D Pickard, David K Menon, T Adrian Carpenter, Peter J Hutchinson, and CarpenterKeri L HKLH1 Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge , Cambridge, United Kingdom .5 Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge , Cambridge, United Ki.
• 1 Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge , Cambridge, United Kingdom .
• J. Neurotrauma. 2018 Sep 1; 35 (17): 2025-2035.

AbstractMetabolic abnormalities occur after traumatic brain injury (TBI). Glucose is conventionally regarded as the major energy substrate, although lactate can also be an energy source. We compared 3-13C lactate metabolism in TBI with "normal" control brain and muscle, measuring 13C-glutamine enrichment to assess tricarboxylic acid (TCA) cycle metabolism. Microdialysis catheters in brains of nine patients with severe TBI, five non-TBI brain surgical patients, and five resting muscle (non-TBI) patients were perfused (24 h in brain, 8 h in muscle) with 8 mmol/L sodium 3-13C lactate. Microdialysate analysis employed ISCUS and nuclear magnetic resonance. In TBI, with 3-13C lactate perfusion, microdialysate glucose concentration increased nonsignificantly (mean +11.9%, p = 0.463), with significant increases (p = 0.028) for lactate (+174%), pyruvate (+35.8%), and lactate/pyruvate ratio (+101.8%). Microdialysate 13C-glutamine fractional enrichments (median, interquartile range) were: for C4 5.1 (0-11.1) % in TBI and 5.7 (4.6-6.8) % in control brain, for C3 0 (0-5.0) % in TBI and 0 (0-0) % in control brain, and for C2 2.9 (0-5.7) % in TBI and 1.8 (0-3.4) % in control brain. 13C-enrichments were not statistically different between TBI and control brain, showing both metabolize 3-13C lactate via TCA cycle, in contrast to muscle. Several patients with TBI exhibited 13C-glutamine enrichment above the non-TBI control range, suggesting lactate oxidative metabolism as a TBI "emergency option."

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