Egar Jeanne, Ali Ahmad, Howlett Susan E, Friesen Camille Hancock, O'Blenes Stacy
Department of Physiology and Biophysics, Dalhousie University, Halifax, Canada.
J Cardiothorac Surg. 2014 Jan 8;9:11. doi: 10.1186/1749-8090-9-11.
The Na+/Ca2+ exchange inhibitor SEA0400 prevents myocardial injury in models of global ischemia and reperfusion. We therefore evaluated its potential as a cardioplegia additive.
Isolated rat cardiomyocytes were exposed to hypoxia (45 min) followed by reperfusion. During hypoxia, cells were protected using cardioplegia with (n=25) or without (n=24) SEA0400 (1 μM), or were not protected with cardioplegia (hypoxic control, n=8). Intracellular Ca2+ levels were measured using Ca2+ sensitive dye (fura-2 AM). Isolated rat hearts were arrested using cardioplegia with (n=7) or without (n=6) SEA0400 (1 μM) then reperfused after 45 min of ischemia. Left ventricular (LV) function, troponin release, and mitochondrial morphology were evaluated.
Cardiomyocytes exposed to hypoxia without cardioplegia had poor survival (13%). Survival was significantly improved when cells were protected with cardioplegia containing SEA0400 (68%, p=0.009); cardioplegia without SEA0400 was associated with intermediate survival (42%). Cardiomyocytes exposed to hypoxia alone had a rapid increase in intracellular Ca2+ (305 ± 123 nM after 20 minutes of ischemia). Increases in intracellular Ca2+ were reduced in cells arrested with cardioplegia without SEA0400; however cardioplegia containing SEA0400 was associated with the lowest intracellular Ca2+ levels (110 ± 17 vs. 156 ± 42 nM after 45 minutes of ischemia, p=0.004). Hearts arrested with cardioplegia containing SEA0400 had better recovery of LV work compared to cardioplegia without SEA0400 (23140 ± 2264 vs. 7750 ± 929 mmHg.μl, p=0.0001). Troponin release during reperfusion was lower (0.6 ± 0.2 vs. 2.4 ± 0.5 ng/mL, p=0.0026), and there were more intact (41 ± 3 vs. 22 ± 5%, p<0.005), and fewer disrupted mitochondria (24 ± 2 vs. 33 ± 3%, p<0.05) in the SEA0400 group.
SEA0400 added to cardioplegia limits accumulation of intracellular Ca2+ during ischemic arrest in isolated cardiomyocytes and prevents myocardial injury and improves recovery of LV function in isolated hearts.
钠/钙交换抑制剂SEA0400可预防全心缺血及再灌注模型中的心肌损伤。因此，我们评估了其作为心脏停搏液添加剂的潜力。
将分离的大鼠心肌细胞暴露于缺氧环境（45分钟）后再灌注。在缺氧期间，使用含（n = 25）或不含（n = 24）SEA0400（1 μM）的心脏停搏液保护细胞，或不使用心脏停搏液进行保护（缺氧对照组，n = 8）。使用钙敏感染料（fura - 2 AM）测量细胞内钙水平。使用含（n = 7）或不含（n = 6）SEA0400（1 μM）的心脏停搏液使分离的大鼠心脏停搏，缺血45分钟后再灌注。评估左心室（LV）功能、肌钙蛋白释放及线粒体形态。
未使用心脏停搏液暴露于缺氧环境的心肌细胞存活率较低（13%）。当使用含SEA0400的心脏停搏液保护细胞时，存活率显著提高（68%，p = 0.009）；不含SEA0400的心脏停搏液的存活率处于中等水平（42%）。单独暴露于缺氧环境的心肌细胞细胞内钙迅速增加（缺血20分钟后为305±123 nM）。使用不含SEA0400的心脏停搏液停搏的细胞内钙增加有所减少；然而，含SEA0400的心脏停搏液与最低的细胞内钙水平相关（缺血45分钟后为110±17 vs. 156±42 nM，p = 0.004）。与不含SEA0400的心脏停搏液相比，使用含SEA0400的心脏停搏液停搏的心脏左心室功能恢复更好（23140±2264 vs. 7750±929 mmHg.μl，p = 0.0001）。再灌注期间肌钙蛋白释放较低（0.6±0.2 vs. 2.4±0.5 ng/mL，p = 0.0026），SEA0400组中完整线粒体更多（41±3 vs. 22±5%，p<0.005），受损线粒体更少（24±2 vs. 33±3%，p<0.05）。
添加到心脏停搏液中的SEA0400可限制分离心肌细胞缺血停搏期间细胞内钙的积累，预防心肌损伤并改善分离心脏的左心室功能恢复。
