Camara Amadou K S, Aldakkak Mohammed, Heisner James S, Rhodes Samhita S, Riess Matthias L, An JiangZhong, Heinen André, Stowe David F
Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
Am J Physiol Cell Physiol. 2007 Jun;292(6):C2021-31. doi: 10.1152/ajpcell.00231.2006. Epub 2007 Feb 7.
We have shown that cold perfusion of hearts generates reactive oxygen and nitrogen species (ROS/RNS). In this study, we determined 1) whether ROS scavenging only during cold perfusion before global ischemia improves mitochondrial and myocardial function, and 2) which ROS leads to compromised cardiac function during ischemia and reperfusion (I/R) injury. Using fluorescence spectrophotometry, we monitored redox balance (NADH and FAD), O(2)(-) levels and mitochondrial Ca(2+) (m[Ca(2+)]) at the left ventricular wall in 120 guinea pig isolated hearts divided into control (Con), MnTBAP (a superoxide dismutase 2 mimetic), MnTBAP (M) + catalase (C) + glutathione (G) (MCG), C+G (CG), and N(G)-nitro-L-arginine methyl ester (L-NAME; a nitric oxide synthase inhibitor) groups. After an initial period of warm perfusion, hearts were treated with drugs before and after at 27 degrees C. Drugs were washed out before 2 h at 27 degrees C ischemia and 2 h at 37 degrees C reperfusion. We found that on reperfusion the MnTBAP group had the worst functional recovery and largest infarction with the highest m[Ca(2+)], most oxidized redox state and increased ROS levels. The MCG group had the best recovery, the smallest infarction, the lowest ROS level, the lowest m[Ca(2+)], and the most reduced redox state. CG and L-NAME groups gave results intermediate to those of the MnTBAP and MCG groups. Our results indicate that the scavenging of cold-induced O(2)(-) species to less toxic downstream products additionally protects during and after cold I/R by preserving mitochondrial function. Because MnTBAP treatment showed the worst functional return along with poor preservation of mitochondrial bioenergetics, accumulation of H(2)O(2) and/or hydroxyl radicals during cold perfusion may be involved in compromised function during subsequent cold I/R injury.
我们已经表明，心脏冷灌注会产生活性氧和氮物种（ROS/RNS）。在本研究中，我们确定了：1）仅在全心缺血前的冷灌注期间清除ROS是否能改善线粒体和心肌功能；2）在缺血再灌注（I/R）损伤期间，哪种ROS会导致心脏功能受损。我们使用荧光分光光度法，监测了120只豚鼠离体心脏左心室壁的氧化还原平衡（NADH和FAD）、O₂⁻水平以及线粒体Ca²⁺（m[Ca²⁺]），这些心脏被分为对照组（Con）、锰（III）四（4 - 苯甲酸）卟啉（MnTBAP，一种超氧化物歧化酶2模拟物）组、MnTBAP（M）+过氧化氢酶（C）+谷胱甘肽（G）（MCG）组、C + G（CG）组以及N⁰-硝基-L-精氨酸甲酯（L-NAME，一种一氧化氮合酶抑制剂）组。在初始的温灌注期后，心脏在27℃时给药，给药前后均进行。在27℃缺血2小时和37℃再灌注2小时前将药物洗脱。我们发现，再灌注时，MnTBAP组功能恢复最差，梗死面积最大，m[Ca²⁺]最高，氧化还原状态最氧化，ROS水平升高。MCG组恢复最好，梗死面积最小，ROS水平最低，m[Ca²⁺]最低，氧化还原状态最还原。CG组和L-NAME组的结果介于MnTBAP组和MCG组之间。我们的结果表明，将冷诱导的O₂⁻物种清除为毒性较小的下游产物，通过保留线粒体功能，在冷I/R期间及之后还能提供额外的保护。因为MnTBAP处理显示出最差的功能恢复以及线粒体生物能量学的保存不佳，冷灌注期间H₂O₂和/或羟基自由基的积累可能与随后的冷I/R损伤期间的功能受损有关。
