Layton M E, Wagner J K, Samson F E, Pazdernik T L
Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City 66160-7417, USA.
Neurochem Res. 1997 Jun;22(6):735-41. doi: 10.1023/a:1027362312381.
Microdialysis probe insertion into rat cerebral cortex significantly affects the levels of redox-active substances in brain extracellular fluid. Ascorbic acid levels are high immediately after probe insertion, decline rapidly, and then rise as the rat recovers from anesthesia 5-8 hours after surgery. Uric acid is at a low level for 5 hours and then rapidly increases in parallel with ascorbic acid. High ascorbic acid levels immediately after probe insertion are likely due to a shift from intracellular to extracellular fluids, whereas the delayed increase in uric acid may be due to increased enzymatic formation. After removal from the brain, hydrogen peroxide (H2O2) in microdialysis samples produces catalase-sensitive oxidative chemiluminescence. Microdialysis samples also produce high level catalase-resistant chemiluminescence associated with ascorbic acid levels after penetration injury. Although ascorbic acid is likely an antioxidant at concentrations estimated to be in brain extracellular fluid, it may have prooxidant effects when complexed with transition metals released into the neuronal microenvironment during traumatic brain injury.
将微透析探针插入大鼠大脑皮层会显著影响脑细胞外液中氧化还原活性物质的水平。探针插入后立即，抗坏血酸水平很高，随后迅速下降，然后随着大鼠在手术后5 - 8小时从麻醉中恢复而上升。尿酸在5小时内处于低水平，然后与抗坏血酸平行迅速增加。探针插入后立即出现的高抗坏血酸水平可能是由于从细胞内液向细胞外液的转移，而尿酸的延迟增加可能是由于酶促形成增加。从大脑中取出后，微透析样品中的过氧化氢（H2O2）会产生过氧化氢酶敏感的氧化化学发光。微透析样品在穿透性损伤后还会产生与抗坏血酸水平相关的高水平过氧化氢酶抗性化学发光。尽管抗坏血酸在估计存在于脑细胞外液中的浓度下可能是一种抗氧化剂，但当它与创伤性脑损伤期间释放到神经元微环境中的过渡金属络合时，可能具有促氧化作用。
