Patet Camille, Quintard Hervé, Suys Tamarah, Bloch Jocelyne, Daniel Roy T, Pellerin Luc, Magistretti Pierre J, Oddo Mauro
1 Department of Intensive Care Medicine, University of Lausanne , Switzerland .
2 Department of Clinical Neurosciences, University of Lausanne , Switzerland .
J Neurotrauma. 2015 Oct 15;32(20):1560-6. doi: 10.1089/neu.2014.3781. Epub 2015 May 26.
Lactate may represent a supplemental fuel for the brain. We examined cerebral lactate metabolism during prolonged brain glucose depletion (GD) in acute brain injury (ABI) patients monitored with cerebral microdialysis (CMD). Sixty episodes of GD (defined as spontaneous decreases of CMD glucose from normal to low [<1.0 mmol/L] for at least 2 h) were identified among 26 patients. During GD, we found a significant increase of CMD lactate (from 4 ± 2.3 to 5.4 ± 2.9 mmol/L), pyruvate (126.9 ± 65.1 to 172.3 ± 74.1 μmol/L), and lactate/pyruvate ratio (LPR; 27 ± 6 to 35 ± 9; all, p < 0.005), while brain oxygen and blood lactate remained normal. Dynamics of lactate and glucose supply during GD were further studied by analyzing the relationships between blood and CMD samples. There was a strong correlation between blood and brain lactate when LPR was normal (r = 0.56; p < 0.0001), while an inverse correlation (r = -0.11; p = 0.04) was observed at elevated LPR >25. The correlation between blood and brain glucose also decreased from r = 0.62 to r = 0.45. These findings in ABI patients suggest increased cerebral lactate delivery in the absence of brain hypoxia when glucose availability is limited and support the concept that lactate acts as alternative fuel.
乳酸可能是大脑的一种补充燃料。我们在急性脑损伤（ABI）患者中，通过脑微透析（CMD）监测，研究了长时间脑葡萄糖耗竭（GD）期间的脑乳酸代谢。在26例患者中识别出60次GD发作（定义为CMD葡萄糖从正常水平自发下降至低水平[<1.0 mmol/L]并持续至少2小时）。在GD期间，我们发现CMD乳酸（从4±2.3 mmol/L增至5.4±2.9 mmol/L）、丙酮酸（从126.9±65.1 μmol/L增至172.3±74.1 μmol/L）和乳酸/丙酮酸比值（LPR；从27±6增至35±9；所有p<0.005）显著增加，而脑氧和血乳酸保持正常。通过分析血样和CMD样本之间的关系，进一步研究了GD期间乳酸和葡萄糖供应的动态变化。当LPR正常时，血乳酸和脑乳酸之间存在强相关性（r = 0.56；p<0.0001），而当LPR>25升高时，观察到负相关性（r = -0.11；p = 0.04）。血葡萄糖和脑葡萄糖之间的相关性也从r = 0.62降至r = 0.45。ABI患者的这些发现表明，在葡萄糖可用性受限且无脑缺氧的情况下，脑乳酸输送增加，并支持乳酸作为替代燃料的概念。
