Olano M, Song D, Murphy S, Wilson D F, Pastuszko A
Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia 19104, USA.
J Neurochem. 1995 Sep;65(3):1205-12. doi: 10.1046/j.1471-4159.1995.65031205.x.
The present study describes the relationships of extracellular striatal dopamine, cortical oxygen pressure, and striatal hydroxyl radicals in brain of newborn piglets during hypoxia and posthypoxic reoxygenation. Hypoxia was induced by reducing the fraction of inspired oxygen (FiO2) from 22% (control) to 7% for 1 h. The FiO2 was then returned to the control value and measurements were continued for 2 h. Cerebral oxygen pressure was measured by the oxygen dependent quenching of phosphorescence and extracellular levels of dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and hydroxy radicals in the striatum were determined by in vivo microdialysis. Hypoxia decreased the cortical oxygen pressure from 47 +/- 2 to 9 +/- 1.3 torr (p < 0.001); the levels of extracellular dopamine in the striatum increased to 16,000 +/- 3,270% of control (p < 0.01), whereas the levels of DOPAC and HVA decreased to 25.3 +/- 6% (p < 0.001) and 36 +/- 5% (p < 0.01) of control, respectively. Compared with control, the hydroxyl radical levels at each time point were not significantly increased during hypoxia, although the sum of the measured values was significantly increased (p < 0.05). During the first 5 min after FiO2 was returned to 22%, the cortical oxygen pressure increased to control values and stayed at this level for the remainder of the measurement period. The extracellular level of dopamine declined to values not statistically different from control during 40 min of reoxygenation. During the first 10 min of reoxygenation, DOPAC and HVA further decreased and then began to slowly increase. By 70 min of reoxygenation, the values were not significantly different from control.(ABSTRACT TRUNCATED AT 250 WORDS)
本研究描述了新生仔猪大脑在缺氧及缺氧后复氧过程中，细胞外纹状体多巴胺、皮质氧分压和纹状体羟自由基之间的关系。通过将吸入氧分数（FiO₂）从22%（对照）降至7%持续1小时诱导缺氧。然后将FiO₂恢复到对照值并继续测量2小时。通过磷光的氧依赖性猝灭测量脑氧分压，通过体内微透析测定纹状体中多巴胺、3,4 - 二羟基苯乙酸（DOPAC）、高香草酸（HVA）和羟自由基的细胞外水平。缺氧使皮质氧分压从47±2降至9±1.3托（p < 0.001）；纹状体中细胞外多巴胺水平增加至对照的16,000±3,270%（p < 0.01），而DOPAC和HVA水平分别降至对照的25.3±6%（p < 0.001）和36±5%（p < 0.01）。与对照相比，缺氧期间各时间点的羟自由基水平虽测量值总和显著增加（p < 0.05），但未显著升高。在FiO₂恢复到22%后的最初5分钟内，皮质氧分压升至对照值并在测量期剩余时间保持在此水平。复氧40分钟期间，多巴胺的细胞外水平降至与对照无统计学差异的值。在复氧的最初10分钟内，DOPAC和HVA进一步下降，然后开始缓慢上升。到复氧70分钟时，其值与对照无显著差异。（摘要截断于250字）
