UCIBIO-Applied Molecular Biosciences Unit, REQUIMTE-Rede de Química e Tecnologia, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, 2829-516 Monte de Caparica, Portugal.
Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal.
Biosensors (Basel). 2021 Aug 17;11(8):277. doi: 10.3390/bios11080277.
The impaired blood flow to the brain causes a decrease in the supply of oxygen that can result in cerebral ischemia; if the blood flow is not restored quickly, neuronal injury or death will occur. Under hypoxic conditions, the production of nitric oxide (NO), via the classical L-arginine-NO synthase pathway, is reduced, which can compromise NO-dependent vasodilation. However, the alternative nitrite (NO) reduction to NO, under neuronal hypoxia and ischemia conditions, has been viewed as an in vivo storage pool of NO, complementing its enzymatic synthesis. Brain research is thus demanding suitable tools to probe nitrite's temporal and spatial dynamics in vivo. In this work, we propose a new method for the real-time measurement of nitrite concentration in the brain extracellular space, using fast-scan cyclic voltammetry (FSCV) and carbon microfiber electrodes as sensing probes. In this way, nitrite was detected anodically and in vitro, in the 5-500 µM range, in the presence of increasing physiological concentrations of ascorbate (100-500 µM). These sensors were then tested for real-time and in vivo recordings in the anesthetized rat hippocampus; using fast electrochemical techniques, local and reproducible transients of nitrite oxidation signals were observed, upon pressure ejection of an exogenous nitrite solution into the brain tissue. Nitrite microsensors are thus a valuable tool for investigating the role of this inorganic anion in brain redox signaling.
脑血流减少导致供氧减少，从而导致脑缺血；如果血流不能迅速恢复，神经元将受到损伤或死亡。在缺氧条件下，通过经典的 L-精氨酸-NO 合酶途径产生的一氧化氮（NO）减少，这会损害依赖 NO 的血管舒张。然而，在神经元缺氧和缺血条件下，亚硝酸盐（NO）替代 NO 还原为 NO 被视为 NO 的体内储存库，补充其酶促合成。因此，脑研究需要合适的工具来探测体内亚硝酸盐的时空动态。在这项工作中，我们提出了一种使用快速扫描循环伏安法（FSCV）和碳纤维微电极作为传感探针实时测量脑细胞外空间中亚硝酸盐浓度的新方法。通过这种方式，在存在生理浓度不断增加的抗坏血酸（100-500 µM）的情况下，亚硝酸盐在体外和 5-500 µM 的范围内被检测到阳极。然后，这些传感器在麻醉大鼠海马体中进行了实时和体内记录测试；使用快速电化学技术，在外源性亚硝酸盐溶液压入脑组织时，观察到局部和可重复的亚硝酸盐氧化信号瞬变。因此，亚硝酸盐微传感器是研究这种无机阴离子在脑氧化还原信号中的作用的有价值工具。
