Silver I A, Erecińska M
Department of Anatomy, School of Veterinary Science, University of Bristol, United Kingdom.
J Neurosci. 1994 Aug;14(8):5068-76. doi: 10.1523/JNEUROSCI.14-08-05068.1994.
The concentration of extracellular glucose in anesthetized rat brain was measured continuously with two types of substrate-specific microelectrodes in a number of physiological and pathological conditions. Extracellular glucose level increased in hyperglycemia and decreased in hypoglycemia, paralleling the changes in blood sugar. Increased neuronal activity and in particular spreading depression, evoked triphasic alterations in extracellular glucose concentration: an initial rapid fall was followed by an equally swift overshoot above the baseline and a subsequent return to it. Limitation in O2 supply led to a decline in extracellular content of glucose: respiration with 5% O2 reduced the level by 7-20% and that with 3% O2 by 75-85%. Decreases to undetectable concentrations were seen in ischemia despite the use of an oxygen-insensitive microglucose sensor. Restoration of oxygen supply to the brain was accompanied by increases in extracellular glucose content above the original normoxic level, which returned to baseline values after 10-15 min. In hyperglycemic animals ischemia-induced leakage of K+ was delayed while the rate of recovery to control levels after restitution of blood flow was enhanced. It is concluded that continuous monitoring of glucose with glucose-specific microelectrodes provides a new and important insight into brain energy metabolism.
在多种生理和病理条件下，使用两种底物特异性微电极连续测量麻醉大鼠大脑中的细胞外葡萄糖浓度。高血糖时细胞外葡萄糖水平升高，低血糖时降低，与血糖变化平行。神经元活动增加，特别是扩散性抑制，会引起细胞外葡萄糖浓度的三相变化：最初迅速下降，随后同样迅速地超过基线水平，随后又回到基线。氧气供应受限导致细胞外葡萄糖含量下降：用5%氧气呼吸使水平降低7-20%，用3%氧气呼吸使水平降低75-85%。尽管使用了对氧不敏感的微葡萄糖传感器，但在缺血时仍可降至无法检测的浓度。恢复大脑的氧气供应伴随着细胞外葡萄糖含量高于原始常氧水平的增加，10-15分钟后恢复到基线值。在高血糖动物中，缺血诱导的钾离子泄漏延迟，而恢复血流后恢复到对照水平的速率加快。结论是，用葡萄糖特异性微电极连续监测葡萄糖为脑能量代谢提供了新的重要见解。
