摘要
目的阐明高气压对脑细胞外液谷氨酸浓度的影响。方法将清醒的７只小鼠在３０分钟内快速加压至４．６ＭＰａＨｅ－Ｏ２环境。采用微透析技术，通过预先植入海马部位的微透析探头收集脑细胞外液，然后用高效液相（ＨＰＬＣ）梯度洗脱分离，以荧光检测法分析氨基酸含量。高压暴露下全过程用连续脑电振幅谱方式监视动物大脑功能状态。结果发现小鼠脑细胞外液谷氨酸浓度在４．６ＭＰａＨｅ－Ｏ２环境下是升高的（透析液中浓度增加了０．２６μｍｏｌ／Ｌ，Ｐ＜０．０５）；脑电的主要变化有振波向低频转移，振幅减弱并阵发性增强及出现尖峰（ｓｐｉｋｅ）等。癫痫样脑电出现在脑细胞外液谷氨酸过度升高的动物。结论以上结果说明高气压下中枢神经系统功能随细胞外液谷氨酸浓度升高而扰乱，是导致高压神经综合征（ＨＰＮＳ）的重要原因。脑细胞外液谷氨酸浓度在高气压下变化的差异可能是ＨＰＮＳ个体差异的原因之一。
Objective To illustrate the effect of high pressure on brain extracellular
glutamate concentration. Methods 7 fully alert mice were rapidly compressed to 4.6 MPa using
heliumoxygen mixture.The microdialysis method was used. The dialytrode was preinserted to
hippocampus and brain extracellular fluid was then collected.The amino acids in it were
analysed by means of HPLC and OPAderivatization.EEG frequency was continuously monitored
and recorded by an EEG trend monitor during the hyperbaric exposure. Results The
extracellular glutamate concentration was found elevated(mean value of 0.26 mol/L increament
in perfusion fluid,P<005)in hippocampus during hyperbaric exposure.Main EEG changes
included:shift of main frequency to lower band,diminished amplitude with paroxysmal
intensification and appearance of spiks.Besides epileptic like EEG was found in the animal with
extraordinarily high extracellular glutamate concentration. Conclusions The above results
demonstrate that excessive extracellular glutamate is an important cause of high pressure
nervous syndrome(HPNS),and the variation in change of glutamate concentration under high
pressure might be the cause of different individual HPNS susceptibility.
