title: Continuous on-line monitoring of extracellular ascorbate depletion in the rat striatum induced by global ischemia with carbon nanotube-modified glassy carbon electrode integrated into a thin-layer radial flow cell.
abstract: This study describes a novel analytical system integrating in vivo microdialysis sampling with a radial thin-layer flow cell with a single-walled carbon nanotube (SWNT)-modified glassy carbon electrode as working electrode for continuous and on-line monitoring of ascorbate depletion in the rat striatum induced by global ischemia. The SWNTs, especially those after vacuum heat treatment at 500 degrees C, are found to be able to enhance the electron-transfer kinetics of ascorbate oxidation at a low potential (ca. -50 mV) and possess a strong ability against electrode fouling. These properties essentially make it possible to determine ascorbate with a good stability and high selectivity against catecholamines and their metabolites and other electroactive species of physiological levels. While being integrated with in vivo microdialysis to assemble an on-line analytical system, the electrode is proved useful for continuous and sensitive monitoring of the basal dialysate level of ascorbate and its depletion in the rat striatum induced by global ischemia. The basal dialysate level of ascorbate is determined to be 5.0 +/- 0.5 microM (n = 5) and a 50 +/- 10% (n = 3) depletion is recorded for the basal ascorbate after 4 h of global ischemia.
authors.affiliation: Center for Molecular Science, Institute of Chemistry, the Chinese Academy of Sciences, Beijing 100080, China.
authors.forename: Meining
authors.initials: M
authors.lastname: Zhang
authors.forename: Kun
authors.initials: K
authors.lastname: Liu
authors.forename: Kuanping
authors.initials: K
authors.lastname: Gong
authors.forename: Lei
authors.initials: L
authors.lastname: Su
authors.forename: Yi
authors.initials: Y
authors.lastname: Chen
authors.forename: Lanqun
authors.initials: L
authors.lastname: Mao
mesh_terms: D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology*; D003342:Corpus Striatum / Q000187:drug effects*; D004563:Electrochemistry; D004566:Electrodes; D005609:Free Radicals; D007511:Ischemia / Q000473:pathology*; D008297:Male; D015394:Molecular Structure; D037742:Nanotubes, Carbon; D009862:Online Systems / Q000295:instrumentation*; D010084:Oxidation-Reduction; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results
chemical_list: D005609:Free Radicals; D037742:Nanotubes, Carbon; D001205:Ascorbic Acid