Knott E Marty, Sun Jie, Lei Yu, Ryou Myoung-Gwi, Olivencia-Yurvati Albert H, Mallet Robert T
Department of Integrative Physiology, University of North Texas Health Science Center, Fort Worth, Texas 76107-2699, USA.
Ann Thorac Surg. 2006 Mar;81(3):928-34. doi: 10.1016/j.athoracsur.2005.08.046.
Cardioplegic arrest and reperfusion of the myocardium imposes oxidative stress that could potentially inactivate metabolic enzymes and compromise energy production. This study determined the impact of cardioplegic arrest and reperfusion on activities of several oxidant-sensitive enzymes, and tested whether pyruvate, a natural metabolic fuel and antioxidant, mitigates oxidant stress, protects enzymes, and bolsters myocardial energy state after reperfusion.
In situ swine hearts were arrested for 60 minutes with 4:1 blood:crystalloid cardioplegia, and then reperfused for 3 minutes with cardioplegia-free blood with or without approximately 12 mM pyruvate. Tissue metabolites and enzyme activities were measured in left ventricular myocardium snap frozen at 45 minutes of arrest and 3 minutes of reperfusion.
The 8-isoprostane content, a measure of lipid peroxidation, sharply increased upon reperfusion, coincident with a 70% decline in redox state of the intracellular antioxidant glutathione. Aconitase and glucose 6-phosphate dehydrogenase activities fell during arrest; creatine kinase and phosphofructokinase were inactivated upon reperfusion. Pyruvate suppressed 8-isoprostane formation, maintained glutathione redox state, and enhanced phosphocreatine phosphorylation potential, a measure of myocardial energy state, during reperfusion. Pyruvate reactivated creatine kinase and aconitase, which are at least partially mitochondrial enzymes, but did not protect the cytosolic enzymes glucose 6-phosphate dehydrogenase and phosphofructokinase.
Administration of pyruvate upon reperfusion after cardioplegic arrest mitigates oxidative stress, protects mitochondrial enzymes and increases myocardial energy state. These results support therapeutic application of pyruvate-enhanced reperfusion to prevent cardiac injury after cardioplegic arrest.
心脏停搏和心肌再灌注会产生氧化应激，这可能会使代谢酶失活并影响能量生成。本研究确定了心脏停搏和再灌注对几种氧化敏感酶活性的影响，并测试了丙酮酸（一种天然代谢燃料和抗氧化剂）是否能减轻氧化应激、保护酶并在再灌注后增强心肌能量状态。
用4:1的血液：晶体心脏停搏液使原位猪心脏停搏60分钟，然后用不含心脏停搏液的血液进行3分钟的再灌注，再灌注血液中添加或不添加约12 mM的丙酮酸。在心脏停搏45分钟和再灌注3分钟时，对左心室心肌进行速冻，测量组织代谢物和酶活性。
作为脂质过氧化指标的8-异前列腺素含量在再灌注时急剧增加，同时细胞内抗氧化剂谷胱甘肽的氧化还原状态下降了70%。乌头酸酶和葡萄糖6-磷酸脱氢酶的活性在心脏停搏期间下降；肌酸激酶和磷酸果糖激酶在再灌注时失活。丙酮酸在再灌注期间抑制了8-异前列腺素的形成，维持了谷胱甘肽的氧化还原状态，并增强了磷酸肌酸磷酸化电位（一种心肌能量状态的指标）。丙酮酸使肌酸激酶和乌头酸酶重新激活，这两种酶至少部分是线粒体酶，但并未保护胞质酶葡萄糖6-磷酸脱氢酶和磷酸果糖激酶。
心脏停搏后再灌注时给予丙酮酸可减轻氧化应激，保护线粒体酶并增加心肌能量状态。这些结果支持丙酮酸增强再灌注在预防心脏停搏后心脏损伤方面的治疗应用。
