KATP通道的谷胱甘肽化作为败血症严重性的标记作用

Severe sepsis/septic shock are the world wide diseases. Septic shock manifests itself as vasodilatation and hyporeactivity to vasoconstrictors, leading to hypotension, hypoperfusion, tissue hypoxia and multiple organ failure. Recent studies indicate that the vascular ATP-sensitive K+ channel (KATP) plays a critical role in sepsis susceptibility. These findings indicate that activation of the KATP is a protective mechanism benefiting the system in response to septic pathogens, whereas KATP dysregulation may be a key contributor to the mortality rate of sepsis. A striking finding was a robust KATP inhibition with a prolonged period of endotoxemia, as a significant loss of the KATP-dependent cardiovascular protection is vital in sepsis/endotoxemia as suggested by the channel knockout studies above. Our preliminary data suggest that the vascular KATP is targeted by multiple septic pathogens or the Toll-like receptor ligands, involving transcriptional and post-translational mechanisms. The objective of this project is to demonstrate the mechanism and the biomarker feasibility for glutathionylation of the KATP in vascular smooth muscles in experimental sepsis. We have therefore proposed studies to address these questions: 1. What causes such a channel inhibition? 2. Does the channel inhibition result from KATP glutathionylation, as oxidative stress is known to be an inflammatory process? 3. Can the KATP glutathionylation be a reliable biomarker of the severity and lethality of sepsis? 4. Can the KATP glutathionylation be alleviated by deglutathionylation agents? The information to be generated should have a profound impact on sepsis treatment and prognosis.

败血症/感染性休克是一种全球多发病，主要表现为机体对血管收缩剂的低反应性，从而导致低血压，组织缺氧和多器官功能衰竭。最近的研究显示，血管平滑肌KATP通道对感染性病原体对机体的刺激起到保护作用，而KATP通道功能失调可能是败血症死亡的重要因素，并会导致KATP依赖性的心血管保护性机制的丧失。我们前期的研究数据表明血管KATP通道是多种感染性病原体或Toll样受体配体的作用靶点，而S-谷胱甘肽化(K-SG)是氧化应激反应中重要的通道调节机制。在此我们拟通过体外实验和动物模型证明下列问题：1.败血症中引起血管KATP通道抑制的机制是什么？2. 在氧化应激状态下起关键作用的K-SG是否为通道的抑制关键因素？3.K-SG是否可以作为败血症严重程度和毁坏性程度的可靠的生物标志物？4.K-SG可否被去谷胱甘肽化试剂所消除? 此项研究对败血症的治疗和预后都具有重要的意义

败血症/感染性休克是一种全球多发病，主要表现为机体对血管收缩剂的低反应性，从而导致低血压，组织缺氧和多器官功能衰竭。最近的研究显示，血管平滑肌KATP 通道对感染性病原体对机体的刺激起到保护作用，而KATP 通道功能失调可能是败血症死亡的重要因素，并会导致KATP 依赖性的心血管保护性机制的丧失。有研究表明，在败血症发生的同时有一氧化氮（NO）大量产生。我们主要研究KATP通道的转录后调节在败血症所引起的血管异常调节中的作用。.我们发现， NO可能是作用于血管平滑肌KATP通道，从而使血管平滑肌张力对血管收缩剂敏感性降低，从而导致低血压。这种调节可能是通过KATP通道的亚硝基化来实现的，而这种亚硝基化又能抑制通道谷胱甘肽化的形成。同时我们也找到了这种亚硝基化可能发生的位点。我们主要采用膜片钳技术直观研究通道活性对NO供体的反应，发现NO能使处于静息状态下的通道开放，但也能够使处于开放状态下的通道部分关闭。当有NO存在时，谷胱甘肽化试剂对通道的抑制作用明显降低。同时利用WB技术检测出在NO存在时，KATP通道中有亚硝基化的发生。基因定点突变后找到了亚硝基化可能发生的位点。此项目可能揭示了败血症引起的机体全身性低血压的发生机制，对败血症的治疗和后期研究都具有重要的意义。