QUANTIFICATION OF QUINOLINIC ACID IN RAT-BRAIN, WHOLE-BLOOD, AND PLASMA BY GAS-CHROMATOGRAPHY AND NEGATIVE CHEMICAL IONIZATION MASS-SPECTROMETRY - EFFECTS OF SYSTEMIC L-TRYPTOPHAN ADMINISTRATION ON BRAIN AND BLOOD QUINOLINIC ACID CONCENTRATIONS
QUANTIFICATION OF QUINOLINIC ACID IN RAT-BRAIN, WHOLE-BLOOD, AND PLASMA BY GAS-CHROMATOGRAPHY AND NEGATIVE CHEMICAL IONIZATION MASS-SPECTROMETRY - EFFECTS OF SYSTEMIC L-TRYPTOPHAN ADMINISTRATION ON BRAIN AND BLOOD QUINOLINIC ACID CONCENTRATIONS
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DOI：
10.1016/0003-2697(88)90556-8
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发表时间：
1988-10-01
影响因子：
2.9
通讯作者：
MARKEY, SP
中科院分区：
文献类型：
--
作者：
HEYES, MP;MARKEY, SP
建立了一种测定脑、全血和血浆中内源性神经毒素喹啉酸(Quin)的气相色谱-质谱法。用负化学电离法获得了高特异性和高灵敏度，以[18O]Quin为内标获得了准确的结果。中和的高氯酸提取物用氯仿洗涤，用于Dowex1次。8(甲酸盐形式)，用6M甲酸洗脱。在三氟乙酰咪唑催化下，奎宁和[18O]奎因分别与六氟异丙醇(质量分别为467和471)进行了酯化反应。用正庚烷提取酯，进样到DB-5毛细管色谱柱。Quin和[18O]Quin通过选择离子监测来自分子阴离子(分别为m/z 467和471)和特定阴离子片段(来自Quin的m/z 316和来自[18O]Quin的m/z 320)的Quin特有的阴离子电流来定量。最低灵敏度为3fmol，批内变异系数为3.2%，批间变异系数为8.1%。L色氨酸(L-色氨酸，0.370 mg/kg)全身给药2小时后，全血和血浆中的奎因浓度分别增加了134.8倍和74.3倍。在额叶皮质，Quin的增加(22.6倍，校正为血液中的Quin)超过皮质L-Trp(2.54倍)、5-羟色胺(1.35倍)和5-HIAA(1.74倍)的增加。这些研究表明，奎宁存在于大脑中，并对全身应用L-色氨酸的有效性敏感。
A gas chromatography/mass spectrometry assay is described to quantify the endogenous neurotoxin quinolinic acid (QUIN) in brain, whole blood, and plasma. High specificity and high sensitivity were obtained by using negative chemical ionization and accuracy was achieved by using [18O]QUIN as internal standard. Neutralized perchloric acid extracts were washed with chloroform, applied to Dowex 1 .times. 8 (formate form), and eluted with 6 M formic acid. After lyophilization, QUIN and [18O]QUIN were esterified with hexafluoroisopropanol (to mass 467 and 471, respectively) using trifluoroacetylimidazole as catalyst. The esters were extracted into heptane and injected onto a gas chromatograph, DB-5 capillary column. QUIN and [18O]QUIN were quantified by selected ion monitoring of QUIN-specific anion currents from the molecular anions (m/z 467 and 471, respectively) and a specific anion fragment (m/z 316 from QUIN and m/z 320 from [18O]QUIN). Minimum sensitivity was 3 fmol, intrassay variability was 3.2% and interassay variability was 8.1%. QUIN concentrations in frontal cortex from over 200 rats ranged from 20 to 180 fmol/mg wet wt. Two hours after systemic L-tryptophan (L-Trp; 0.370 mmol/kg) administration, QUIN increased in whole blood 134.8-fold and in plasma, 74.3-fold. In frontal cortex, increases in QUIN (22.6-fold, corrected for QUIN in blood) exceeded increases in cortical L-Trp (2.54-fold), 5-HT (1.35-fold), and 5-HIAA (1.74-fold). These studies demonstrate that QUIN is present in brain and is sensitive to the availability of systemic L-Trp.