Kelly F J, Tetley T D
Cardiovascular Research, The Rayne Institute, St. Thomas' Hospital, London SE1 7EH.
Biochem J. 1997 Jul 1;325 ( Pt 1)(Pt 1):95-9. doi: 10.1042/bj3250095.
The aim of this study was to determine the kinetics of the reactions between the gaseous free-radical pollutant, nitrogen dioxide (NO2), and the water-soluble antioxidants present in respiratory tract lining fluid (RTLF). Samples of RTLF, recovered from 12 subjects (mean age 54.1+/-16.3 years; eight male, four female) as bronchoalveolar lavage (BAL) fluid were exposed ex vivo to NO2 [50-1000 parts per billion (ppb)] for 4 h. For comparison, similar exposures were carried out with single and composite solutions with relevant RTLF antioxidant concentrations. Ascorbic acid (AA), uric acid (UA), GSH depletion, and GSSG and malondialdehyde (MDA) formation were determined with time. In the three models, UA and AA were consumed in a time- and NO2-concentration-related fashion. In addition, their rate of depletion correlated positively with their initial concentration (UA, r=0.92, P<0.05; AA, r=0.94, P<0.05). Little difference was found between the rate of loss of AA (2.2+/-0. 2; 1.9+/-0.5; 1.4+/-0.3 nmol.l-1.h-1.ppb-1), and that of UA (2.4+/-0. 2; 2.1+/-0.6; 1.3+/-0.2 nmol.l-1.h-1.ppb-1) in the three RTLF models examined (single, composite, BAL fluid respectively). GSH loss from BAL fluid (0.2+/-0.1) was significantly less than that seen in either single (1.4+/-0.3) or composite (1.2+/-0.5 nmol.l-1.h-1. ppb-1) antioxidant solutions. In all cases, GSH consumption was significantly less than AA or UA. As model complexity increased, the rate of individual antioxidant loss decreased, such that in BAL fluid, AA, UA and GSH consumption rates were significantly less (P<0. 05) than in the pure or composite antioxidant mixtures. In BAL fluid, little GSSG production was observed at any NO2 concentration. MDA concentration, determined as a measure of lipid peroxidation, did not change following exposure to 50, 150 or 400 ppb NO2, but increased MDA was seen in BAL fluid from 8/12 subjects following exposure to 1000 ppb NO2 for 1 h or more. In conclusion, NO2, at environmentally relevant concentrations, depletes BAL fluid of the antioxidant defences, UA and AA, but not GSH.
本研究的目的是确定气态自由基污染物二氧化氮（NO₂）与呼吸道内衬液（RTLF）中存在的水溶性抗氧化剂之间反应的动力学。从12名受试者（平均年龄54.1±16.3岁；8名男性，4名女性）回收的RTLF样本作为支气管肺泡灌洗（BAL）液，在体外暴露于NO₂[50 - 1000十亿分率（ppb）] 4小时。为作比较，用具有相关RTLF抗氧化剂浓度的单一和复合溶液进行类似暴露。随着时间的推移，测定了抗坏血酸（AA）、尿酸（UA）、谷胱甘肽（GSH）消耗以及氧化型谷胱甘肽（GSSG）和丙二醛（MDA）的形成。在这三种模型中，UA和AA以与时间和NO₂浓度相关的方式被消耗。此外，它们的消耗速率与它们的初始浓度呈正相关（UA，r = 0.92，P < 0.05；AA，r = 0.94，P < 0.05）。在所研究的三种RTLF模型（分别为单一、复合、BAL液）中，AA的损失速率（2.2±0.2；1.9±0.5；1.4±0.3 nmol·L⁻¹·h⁻¹·ppb⁻¹）与UA的损失速率（2.4±0.2；2.1±0.6；1.3±0.2 nmol·L⁻¹·h⁻¹·ppb⁻¹）之间差异不大。BAL液中GSH的损失（0.2±0.1）明显低于单一抗氧化剂溶液（1.4±0.3）或复合抗氧化剂溶液（1.2±0.5 nmol·L⁻¹·h⁻¹·ppb⁻¹）中的损失。在所有情况下，GSH的消耗明显低于AA或UA。随着模型复杂性增加，单个抗氧化剂的损失速率降低，因此在BAL液中，AA、UA和GSH的消耗速率明显低于（P < 0.05）纯的或复合抗氧化剂混合物中的消耗速率。在BAL液中，在任何NO₂浓度下均未观察到大量GSSG产生。作为脂质过氧化指标测定的MDA浓度，在暴露于50、150或400 ppb NO₂后没有变化，但在12名受试者中的8名受试者的BAL液中，在暴露于1000 ppb NO₂ 1小时或更长时间后，MDA有所增加。总之，在与环境相关的浓度下，NO₂会消耗BAL液中的抗氧化防御物质UA和AA，但不会消耗GSH。
