Tucci S, Rada P, Sepúlveda M J, Hernandez L
Department of Physiology, Los Andes University, Merida, Venezuela.
J Chromatogr B Biomed Sci Appl. 1997 Jul 4;694(2):343-9. doi: 10.1016/s0378-4347(96)00488-4.
In the present experiment the combination of brain microdialysis and CZE-LIFD permitted the measurement of glutamate in 100 nl microdialysis samples collected every 5 or 6 s. Samples were collected every 6 s, in rats anesthetized with two different anesthetic agents (ketamine and sodium thiopental). A microdialysis probe was inserted in the cortex of an anesthetized rat in the territory irrigated by the middle cerebral artery. The artery was clamped for 30 s and then released. The samples were derivatized with fluorescein isothiocyanate I (FITC) by means of a continuous-flow reactor, collected and injected into a home-made CZE-LIFD instrument. Glutamate decreased immediately after clamping the artery in ketamine anesthetized rats and increased 1 min after the onset of the ischemia in sodium thiopental anesthetized rats. In another experiment a 60 mM KCl solution was injected through a microdialysis probe inserted in the hippocampus of an anesthetized rat. In the first 5 s after the KCl solution reached the tissue, glutamate increased but gamma-aminobutytic acid and glutamine did not. The experiments show that time resolution of brain microdialysis can be reduced to a few seconds if the analytical technique is the proper one.
在本实验中，脑微透析与毛细管区带电泳-激光诱导荧光检测（CZE-LIFD）相结合，能够对每5或6秒收集一次的100 nl微透析样品中的谷氨酸进行测量。在使用两种不同麻醉剂（氯胺酮和硫喷妥钠）麻醉的大鼠中，每6秒收集一次样品。将微透析探针插入大脑中动脉供血区域的麻醉大鼠的皮质中。夹闭该动脉30秒，然后松开。样品通过连续流动反应器用异硫氰酸荧光素I（FITC）进行衍生化，收集后注入自制的CZE-LIFD仪器中。在氯胺酮麻醉的大鼠中，夹闭动脉后谷氨酸立即下降，而在硫喷妥钠麻醉的大鼠中，缺血开始1分钟后谷氨酸增加。在另一项实验中，通过插入麻醉大鼠海马体的微透析探针注射60 mM KCl溶液。在KCl溶液到达组织后的前5秒内，谷氨酸增加，但γ-氨基丁酸和谷氨酰胺没有增加。这些实验表明，如果采用合适的分析技术，脑微透析的时间分辨率可以降低到几秒。
