Ronne-Engström E, Carlson H, Liu Y, Ungerstedt U, Hillered L
Department of Neurosurgery, Uppsala University Hospital, Sweden.
J Neurochem. 1995 Jul;65(1):257-62. doi: 10.1046/j.1471-4159.1995.65010257.x.
The aim of this study was to evaluate the influence of perfusion media with different glucose concentrations on dialysate levels of lactate, pyruvate, aspartate (Asp), and glutamate (Glu) under basal and hypoxic conditions in rat brain neocortex. Intracerebral microdialysis was performed with the rat under general anesthesia using bilateral probes (o.d. 0.3 mm; membrane length, 2 mm) perfused with artificial CSF containing 0.0 and 3.0 mM glucose, respectively. Basal dialysate levels were obtained 2 h after probe implantation in artificially ventilated animals. Dialysate levels of glucose were also measured for the two different perfusion fluids. The mean absolute extracellular concentration of glucose was estimated by a modification of the no-net-flux method to be 3.3 mmol/L, corresponding to an average in vivo recovery of 6% for glucose. Hypoxia was induced by lowering the inspired oxygen concentration to 3%. Hypoxia caused a disturbance of cortical electrical activity, evidenced by slower frequency and lower amplitudes on the electroencephalogram compared with prehypoxic conditions. This was associated with significant elevations of lactate, Asp, and Glu levels. There were no statistically significant difference in dialysate metabolite levels between the two perfusion fluids, during either normal or hypoxic conditions. We conclude that microdialysis with glucose-free perfusion fluid does not drain brain extracellular glucose in anesthetized rats to the extent that the dialysate lactate, pyruvate, Asp, and Glu levels during basal or hypoxic conditions are altered.
本研究旨在评估在基础条件和缺氧条件下，不同葡萄糖浓度的灌注介质对大鼠脑新皮质透析液中乳酸、丙酮酸、天冬氨酸（Asp）和谷氨酸（Glu）水平的影响。在全身麻醉下，对大鼠进行脑内微透析，使用双侧探针（外径0.3 mm；膜长2 mm），分别用含0.0和3.0 mM葡萄糖的人工脑脊液进行灌注。在人工通气的动物中，探针植入2小时后获取基础透析液水平。还测量了两种不同灌注液的葡萄糖透析液水平。通过对无净通量法的改进，估计葡萄糖的平均绝对细胞外浓度为3.3 mmol/L，对应于葡萄糖在体内的平均回收率为6%。通过将吸入氧浓度降至3%来诱导缺氧。缺氧导致皮质电活动紊乱，脑电图显示与缺氧前相比频率减慢、振幅降低。这与乳酸、Asp和Glu水平的显著升高有关。在正常或缺氧条件下，两种灌注液的透析液代谢物水平均无统计学显著差异。我们得出结论，在麻醉大鼠中，使用无葡萄糖灌注液进行微透析不会将细胞外葡萄糖排出到改变基础或缺氧条件下透析液中乳酸、丙酮酸、Asp和Glu水平的程度。
