Gupte Rakhee S, Vijay Venkataramana, Marks Brian, Levine Robert J, Sabbah Hani N, Wolin Michael S, Recchia Fabio A, Gupte Sachin A
Department of Physiology, New York Medical College, Valhalla, New York 10595, USA.
J Card Fail. 2007 Aug;13(6):497-506. doi: 10.1016/j.cardfail.2007.04.003.
We previously found that higher NADPH levels produced by glucose-6-phosphate dehydrogenase (G6PD) can enhance myocardial superoxide generation by NAD(P)H oxidase in a dog model of dilated cardiomyopathy. Therefore, we tested whether G6PD activity is elevated and enhances NADPH level and increases NAD(P)H oxidase-derived superoxide production in the myocardium from patients with heart failure from ischemic cardiomyopathy.
Surgical discards of left ventricle were collected from 8 congestive heart failure patients undergoing surgical ventricular restoration procedures, whereas control left ventricle tissue was obtained from 5 normal donor hearts deemed not suitable for transplantation. Biochemical assays were performed in tissue homogenates. We found that superoxide and hydrogen peroxide were elevated, respectively, by 9- and 3-fold in failing versus normal hearts (P < .05). The NAD(P)H oxidase inhibitors gp91(ds-tat), apocynin, and diphenyleneiodonium, significantly inhibited superoxide generation by approximately 75%, 89%, and 91%, respectively. Superoxide production by NAD(P)H oxidase increased 10- and 3-fold by adding NADPH (100 micromol/L) and NADH (100 micromol/L), respectively, in a DPI- and gp91(ds-tat)-inhibitable manner. Interestingly, chelerythrine, a PKC inhibitor, and PP2, a Src kinase family inhibitor, reduced G6PD activity (0.29 +/- 0.04 nM x min x mg protein) by 50% and 51% and these inhibitors also decreased myocardial superoxide by 99% and 79%, respectively. Furthermore, 6-aminonicotinamide, a G6PD inhibitor, decreased myocardial superoxide production by 71%.
These data suggest that high NAD(P)H oxidase, fueled by G6PD-derived NADPH, generates most of the superoxide in failing hearts of patients with ischemic cardiomyopathy. In addition, PKC-Src kinase signaling pathways seem to coordinate the activation of both G6PD and NAD(P)H oxidase in human cardiac muscle.
我们之前发现，在扩张型心肌病犬模型中，葡萄糖-6-磷酸脱氢酶（G6PD）产生的较高烟酰胺腺嘌呤二核苷酸磷酸（NADPH）水平可通过NAD（P）H氧化酶增强心肌超氧化物的生成。因此，我们测试了G6PD活性是否升高，是否增强了NADPH水平，并增加了缺血性心肌病心力衰竭患者心肌中NAD（P）H氧化酶衍生的超氧化物生成。
从8例接受外科心室修复手术的充血性心力衰竭患者中收集左心室手术废弃组织，而对照左心室组织取自5例被认为不适合移植的正常供体心脏。在组织匀浆中进行生化分析。我们发现，与正常心脏相比，衰竭心脏中的超氧化物和过氧化氢分别升高了9倍和3倍（P < 0.05）。NAD（P）H氧化酶抑制剂gp91（ds-tat）、阿朴吗啡和二苯碘鎓分别显著抑制超氧化物生成约75%、89%和91%。通过分别添加NADPH（100 μmol/L）和NADH（100 μmol/L），NAD（P）H氧化酶产生的超氧化物分别增加了10倍和3倍，且这种增加可被二苯碘鎓和gp91（ds-tat）抑制。有趣的是，蛋白激酶C（PKC）抑制剂白屈菜红碱和Src激酶家族抑制剂PP2使G6PD活性（0.29 ± 0.04 nM·min·mg蛋白）降低了50%和51%，并且这些抑制剂还分别使心肌超氧化物减少了99%和79%。此外，G6PD抑制剂6-氨基烟酰胺使心肌超氧化物生成减少了71%。
这些数据表明，在缺血性心肌病心力衰竭患者的衰竭心脏中，由G6PD衍生的NADPH驱动的高活性NAD（P）H氧化酶产生了大部分超氧化物。此外，PKC-Src激酶信号通路似乎在人体心肌中协调了G6PD和NAD（P）H氧化酶的激活。
