Sugahara M, Asai S, Zhao H, Nagata T, Kunimatsu T, Ishii Y, Kohno T, Ishikawa K
Department of Pharmacology, Nihon University School of Medicine, Oyaguchi-Kami Machi, Itabashi-ku, 173, Tokyo, Japan.
Neurochem Int. 2001 Jul;39(1):65-73. doi: 10.1016/s0197-0186(00)00109-1.
Our newly developed method using a dialysis electrode has made it possible to perform real time monitoring of extracellular glutamate concentration ([Glu]e) utilizing the oxygen-independent reaction with glutamate oxidase and ferrocene. In this study, we therefore, investigated [Glu]e changes during brain ischemia using both the conventional microdialysis method and the dialysis electrode method. A comparison between our newly developed dialysis electrode and conventional microdialysis methods provided the following results. When the conventional microdialysis method was employed: (1) the elevation of [Glu]e during complete global ischemia was delayed; and (2) the elevation of concentration and reuptake of glutamate were delayed during 10-min transient ischemia, and the elevation of [Glu]e reached a maximum later using conventional microdialysis than using our dialysis electrode. (3) The biphasic [Glu]e elevation of glutamate concentration detected using the dialysis electrode method was not observed using the conventional microdialysis method. It was additionally investigated why the conventional microdialysis method provides inferior time resolution. In this study, we also demonstrated with the chromatographic SMART procedure coupled to UV detection that biogenic substances, i.e. low molecular weight proteins and peptides, are released during ischemic injury, and they may cause a delay in the time resolution in the microdialysis method.
我们新开发的使用透析电极的方法，使得利用谷氨酸氧化酶和二茂铁的非氧依赖反应对细胞外谷氨酸浓度（[Glu]e）进行实时监测成为可能。因此，在本研究中，我们使用传统微透析法和透析电极法研究了脑缺血期间[Glu]e的变化。我们新开发的透析电极与传统微透析方法的比较得出了以下结果。当采用传统微透析法时：（1）完全性全脑缺血期间[Glu]e的升高出现延迟；（2）在10分钟短暂性缺血期间，谷氨酸浓度的升高和再摄取出现延迟，并且使用传统微透析法时[Glu]e的升高达到最大值的时间比使用我们的透析电极时更晚。（3）使用透析电极法检测到的谷氨酸浓度的双相[Glu]e升高在使用传统微透析法时未观察到。此外，还研究了为什么传统微透析法的时间分辨率较差。在本研究中，我们还通过与紫外检测联用的色谱SMART程序证明，生物活性物质，即低分子量蛋白质和肽，在缺血性损伤期间会释放，并且它们可能导致微透析法的时间分辨率延迟。
