Faculty of Medicine, Udayana University, Denpasar, Bali, Indonesia.
J Appl Physiol (1985). 2012 Sep 1;113(5):775-84. doi: 10.1152/japplphysiol.01153.2011. Epub 2012 Jul 12.
This study aimed at determining whether glucose-insulin-potassium (GIK) solutions modify the NADH/NAD(+) ratio during postischemic reperfusion and whether their cardioprotective effect can be attributed to this change in part through reduction of the mitochondrial reactive oxygen species (ROS) production. The hearts of 72 rats were perfused with a buffer containing glucose (5.5 mM) and hexanoate (0.5 mM). They were maintained in normoxia for 30 min and then subjected to low-flow ischemia (0.5% of the preischemic coronary flow for 20 min) followed by reperfusion (45 min). From the beginning of ischemia, the perfusate was subjected to various changes: enrichment with GIK solution, enrichment with lactate (2 mM), enrichment with pyruvate (2 mM), enrichment with pyruvate (2 mM) plus ethanol (2 mM), or no change for the control group. Left ventricular developed pressure, heart rate, coronary flow, and oxygen consumption were monitored throughout. The lactate/pyruvate ratio of the coronary effluent, known to reflect the cytosolic NADH/NAD(+) ratio and the fructose-6-phosphate/dihydroxyacetone-phosphate (F6P/DHAP) ratio of the reperfused myocardium, were evaluated. Mitochondrial ROS production was also estimated. The GIK solution improved the recovery of mechanical function during reperfusion. This was associated with an enhanced cytosolic NADH/NAD(+) ratio and reduced mitochondrial ROS production. The cardioprotection was also observed when the hearts were perfused with fluids known to increase the cytosolic NADH/NAD(+) ratio (lactate, pyruvate plus ethanol) compared with the other fluids (control and pyruvate groups). The hearts with a high mechanical recovery also displayed a low F6P/DHAP ratio, suggesting that an accelerated glycolysis rate may be responsible for increased cytosolic NADH production. In conclusion, the cardioprotection induced by GIK solutions could occur through an increase in the cytosolic NADH/NAD(+) ratio, leading to a decrease in mitochondrial ROS production.
本研究旨在确定葡萄糖-胰岛素-钾（GIK）溶液是否会在缺血后再灌注期间改变 NADH/NAD(+) 比值，以及它们的心脏保护作用是否部分归因于通过减少线粒体活性氧（ROS）产生来实现这一变化。72 只大鼠的心脏用含有葡萄糖（5.5mM）和己酸（0.5mM）的缓冲液灌注。它们在常氧下维持 30 分钟，然后进行低流量缺血（缺血前冠状动脉流量的 0.5%，持续 20 分钟），随后再灌注（45 分钟）。从缺血开始，灌流液就经历了各种变化：GIK 溶液富集、乳酸（2mM）富集、丙酮酸（2mM）富集、丙酮酸（2mM）加乙醇（2mM）富集或对照组无变化。左心室发展压、心率、冠状动脉流量和耗氧量在整个过程中均受到监测。评估冠状流出物中的乳酸/丙酮酸比值，已知该比值反映细胞溶质 NADH/NAD(+) 比值和再灌注心肌中的果糖-6-磷酸/二羟丙酮磷酸（F6P/DHAP）比值。还估计了线粒体 ROS 的产生。GIK 溶液改善了再灌注期间机械功能的恢复。这与增强的细胞溶质 NADH/NAD(+) 比值和减少的线粒体 ROS 产生有关。当心脏用已知能增加细胞溶质 NADH/NAD(+) 比值的液体（乳酸、丙酮酸加乙醇）而不是其他液体（对照组和丙酮酸组）进行灌注时，也观察到了心脏保护作用。具有高机械恢复的心脏也显示出低 F6P/DHAP 比值，表明加速的糖酵解速率可能导致细胞溶质 NADH 产生增加。总之，GIK 溶液诱导的心脏保护作用可能通过增加细胞溶质 NADH/NAD(+) 比值，从而减少线粒体 ROS 的产生来实现。
