Venardos Kylie M, Rajapakse Niwanthi W, Williams David, Hoe Louise S, Peart Jason N, Kaye David M
Baker IDI Heart and Diabetes Institute, Melbourne, Australia.
Baker IDI Heart and Diabetes Institute, Melbourne, Australia; Department of Physiology, Monash University, Melbourne, Australia.
Eur J Pharmacol. 2015 Dec 15;769:64-70. doi: 10.1016/j.ejphar.2015.10.046. Epub 2015 Oct 30.
Reduced nitric oxide (NO) bioavailability plays a central role in the pathogenesis of myocardial ischemia-reperfusion injury (I-R), and reduced l-arginine transport via cationic amino acid transporter-1 is a key contributor to the reduced NO levels. Insulin can increase NO levels by increasing the transport of its substrate l-arginine but insulin alone exerts minimal cardiac protection in I-R. We hypothesized that combined insulin and l-arginine may provide cardioprotective effects in the setting of myocardial I-R. The effect of supplemental insulin, l-arginine and the combination was examined in cardiomyocytes exposed to hypoxia/reoxygenation and in isolated perfused mouse hearts undergoing ischemia/reperfusion. When compared to controls, cardiomyocytes treated upon reoxygenation with 1nM insulin+1mM l-arginine exhibited significant (all P<0.05) improvements in NO generation and mitochondrial membrane potential, with a concomitant fall in reactive oxygen species production and LDH release. Insulin also increased l-arginine uptake following hypoxia-reoxygenation (P<0.05; n=4-6). In langendorff perfused isolated mouse hearts, combined l-arginine-insulin treatment upon reperfusion significantly (all P<0.05; n=9-11) improved recovery of left ventricular developed pressure, rate pressure product and end diastolic pressure following ischemia, independent of any changes in post-ischemic coronary flow, together with significantly lower LDH release. The observed improvements were greater than l-arginine or insulin treatment alone. In isolated cardiomyocytes (n=3-5), 1nM insulin caused cationic amino acid transporter-1 to redistribute to the cellular membrane from the cytosol and the effects of insulin on l-arginine uptake were partially dependent on the PI3K/Akt pathway. l-arginine-insulin treatment may be a novel strategy to ameliorate I-R injury.
一氧化氮（NO）生物利用度降低在心肌缺血再灌注损伤（I-R）的发病机制中起核心作用，而通过阳离子氨基酸转运体-1的L-精氨酸转运减少是NO水平降低的关键因素。胰岛素可通过增加其底物L-精氨酸的转运来提高NO水平，但单独使用胰岛素对I-R的心脏保护作用微乎其微。我们推测，联合使用胰岛素和L-精氨酸可能在心肌I-R情况下提供心脏保护作用。在暴露于缺氧/复氧的心肌细胞以及经历缺血/再灌注的离体灌注小鼠心脏中，研究了补充胰岛素、L-精氨酸及其组合的效果。与对照组相比，复氧时用1nM胰岛素 + 1mM L-精氨酸处理的心肌细胞在NO生成和线粒体膜电位方面有显著改善（所有P<0.05），同时活性氧生成和乳酸脱氢酶释放减少。胰岛素还增加了缺氧复氧后的L-精氨酸摄取（P<0.05；n = 4 - 6）。在Langendorff灌注的离体小鼠心脏中，再灌注时联合L-精氨酸 - 胰岛素处理显著（所有P<0.05；n = 9 - 11）改善了缺血后左心室舒张末压、心率血压乘积和舒张末期压力的恢复，与缺血后冠状动脉血流的任何变化无关，同时乳酸脱氢酶释放显著降低。观察到的改善大于单独使用L-精氨酸或胰岛素治疗。在离体心肌细胞（n = 3 - 5）中，1nM胰岛素使阳离子氨基酸转运体-1从细胞质重新分布到细胞膜，胰岛素对L-精氨酸摄取的影响部分依赖于PI3K/Akt途径。L-精氨酸 - 胰岛素治疗可能是改善I-R损伤的一种新策略。
