Toufektsian M C, Tanguy S, Jeunet A, de Leiris J G, Boucher F R
Laboratoire Stress Cardiovasculaires et des Pathologies Associées, Université Joseph Fourier, Grenoble, France.
Free Radic Res. 2000 Oct;33(4):393-405. doi: 10.1080/10715760000300931.
Oxygen radical scavengers have been shown to prevent the development of ischemic preconditioning, suggesting that reactive oxygen species (ROS) might be involved in this phenomenon. In the present study, we have investigated whether direct exposure to ROS produced by photoactivated Rose Bengal (RB) could mimic the protective effects of ischemic preconditioning.
In vitro generation of ROS from photoactivated RB in a physiological buffer was first characterised by ESR spectroscopy in the presence of 2,2,6,6-tetramethyl-1-piperidone (oxoTEMP) or 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). In a second part of the study, isolated rat hearts were exposed for 2.5 min to photoactivated RB. After 5 min washout, hearts underwent 30 min no-flow normothermic ischemia followed by 30 min of reperfusion.
The production of singlet oxygen (1O2) by photoactivated RB in the perfusion medium was evidenced by the ESR detection of the nitroxyl radical oxoTEMPO. Histidine completely inhibited oxoTEMPO formation. In addition, the use of DMPO has indicated that (i) superoxide anions (O2*-) are produced directly and (ii) hydroxyl radicals (HO*) are formed indirectly from the successive O2*- dismutation and the Fenton reaction. In the perfusion experiments, myocardial post-ischemic recovery was dramatically impaired in hearts previously exposed to the ROS produced by RB photoactivation (1O2, O2*-, H2O2 and HO*) as well as when 1O2 was removed by histidine (50 mM) addition. However, functional recovery was significantly improved when hearts were exposed to photoactivated RB in presence of superoxide dismutase (10(5) IU/L) and catalase (10(6) IU/L). Further studies are now required to determine whether the cardioprotective effects of Rose Bengal in presence of O2*- and H2O2 scavengers are due to singlet oxygen or to other species produced by Rose Bengal degradation.
氧自由基清除剂已被证明可阻止缺血预处理的发展，这表明活性氧（ROS）可能参与了这一现象。在本研究中，我们调查了直接暴露于光活化孟加拉玫瑰红（RB）产生的ROS是否能模拟缺血预处理的保护作用。
首先在生理缓冲液中，通过电子顺磁共振光谱法（ESR）在存在2,2,6,6 - 四甲基 - 1 - 哌啶酮（氧代四甲基哌啶醇，oxoTEMP）或5,5 - 二甲基 - 1 - 吡咯啉 - N - 氧化物（DMPO）的情况下，对光活化RB产生的ROS进行体外表征。在研究的第二部分，将离体大鼠心脏暴露于光活化RB 2.5分钟。冲洗5分钟后，心脏经历30分钟无血流常温缺血，随后再灌注30分钟。
通过ESR检测到硝酰自由基氧代四甲基哌啶醇，证明了光活化RB在灌注介质中产生单线态氧（1O2）。组氨酸完全抑制了氧代四甲基哌啶醇的形成。此外，使用DMPO表明：（i）超氧阴离子（O2 * - ）直接产生，（ii）羟基自由基（HO * ）由连续的O2 * - 歧化反应和芬顿反应间接形成。在灌注实验中，先前暴露于RB光活化产生的ROS（1O2、O2 * - 、H2O2和HO * ）的心脏，以及添加组氨酸（50 mM）去除1O2时，心肌缺血后恢复显著受损。然而，当心脏在存在超氧化物歧化酶（10^5 IU/L）和过氧化氢酶（10^6 IU/L）的情况下暴露于光活化RB时，功能恢复得到显著改善。现在需要进一步研究以确定在存在O2 * - 和H2O2清除剂的情况下，孟加拉玫瑰红的心脏保护作用是由于单线态氧还是由于孟加拉玫瑰红降解产生的其他物质。
