Endothelin Converting Enzyme in Sepsis: Cardiac Function

脓毒症中的内皮素转换酶：心脏功能

• 批准号: 6555990
• 负责人: AVADHESH C SHARMA
• 金额: $ 10.1万
• 依托单位: NORTH DAKOTA STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2005-09-23
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6555990
• 关键词: aspartic endopeptidases; cardiac myocytes; cardiovascular injury; endothelin; heart function; laboratory rat; mitogen activated protein kinase; muscle proteins; myocardium disorder; nitric oxide synthase; pathologic process; protease inhibitor; septicemia; tissue /cell culture

DESCRIPTION (provided by applicant): The long-term objective of our group is to characterize an interactive role of vasoactive substances in sepsis-induced myocardial dysfunction and related cardiovascular pathologies. Chronic peritoneal sepsis in our rat model produces myocardial dysfunction in an isolated heart preparation and cardiomyocytes. Induction of sepsis also increases susceptibility of the isolated hearts to a calcium paradox-mediated myocardial injury. In vivo, we have demonstrated that induction of sepsis results in disproportionate alterations in the circulating levels of Endothelin-1 (ET-1) and nitric oxide byproducts (nitrite and nitrate, NOx). Recently we observed that inhibition of metalloprotease (endothelin-converting enzyme [ECE], which converts proET-1 to ET-1) at the time of induction of endotoxemia decreased the expression of myocardial inducible nitric oxide synthase (iNOS) and downregulated the expression of p38 mitogen-activated protein kinase (MAPK) twenty-four hours later. Therefore, our immediate objective in the present proposal is to test the hypothesis that sepsis-induced alteration in the biosynthesis of myocardial ET-1 (regulated by ECE-1) via MAPK-dependent or -independent mechanism(s) would affect NOS proteins and cardiac function. The following two specific aims are designed to address this hypothesis. Specific Aim 1: To determine if ECE-1 inhibition at the time of induction of sepsis would affect sepsis-induced myocardial dysfunction (decrease in the rates of left ventricular contraction and relaxation, i.e., + dP/dt and -dP/ dt respectively) and the expression of p38MAPK and iNOS proteins at 12 and 24 h post sepsis (Year 1-2). Specific Aim 2: To determine if ECE-1 inhibition at the time of induction of sepsis via p38MAPK-dependent or -independent mechanism would affect myocardial function in an isolated heart preparation at 24 h post sepsis (Year 2-3). The specific aims were designed to assess if ECE-1 inhibition during sepsis would suppress sepsis-induced myocardial dysfunction characterized by downregulation of p38 MAPK and depressed expression of iNOS proteins. The novel aspect of the specific aims is that the results will provide evidence for a causal relationship between ET-1 biosynthesis and the expression of p38MAPK and iNOS proteins in the myocardium. An increased understanding of the underlying mechanisms during these two stages (12 and 24 h post sepsis) of sepsis will help design therapeutic interventions for early and late stages of sepsis.

描述（由申请人提供）：我们小组的长期目标是表征血管活性物质在脓毒症引起的心肌功能障碍和相关心血管病理中的相互作用作用。我们的大鼠模型中的慢性腹膜脓毒症在离体心脏制剂和心肌细胞中产生心肌功能障碍。败血症的诱发还增加了离体心脏对钙悖论介导的心肌损伤的易感性。在体内，我们已经证明败血症的诱导会导致内皮素-1 (ET-1) 和一氧化氮副产物（亚硝酸盐和硝酸盐，NOx）的循环水平发生不成比例的改变。 最近我们观察到，在内毒素血症诱导时抑制金属蛋白酶（内皮素转换酶 [ECE]，将 proET-1 转化为 ET-1）会降低心肌诱导型一氧化氮合酶 (iNOS) 的表达，并在 24 小时后下调 p38 丝裂原激活蛋白激酶 (MAPK) 的表达。因此，我们在本提案中的直接目标是测试以下假设：脓毒症通过 MAPK 依赖或独立机制诱导心肌 ET-1（由 ECE-1 调节）生物合成的改变会影响 NOS 蛋白和心脏功能。以下两个具体目标旨在解决这一假设。 具体目标 1：确定诱导脓毒症时抑制 ECE-1 是否会影响脓毒症引起的心肌功能障碍（左心室收缩率和舒张率分别降低，即 + dP/dt 和 -dP/dt）以及脓毒症后 12 小时和 24 小时（第 1-2 年）p38MAPK 和 iNOS 蛋白的表达。 具体目标 2：确定在通过 p38MAPK 依赖或独立机制诱导脓毒症时 ECE-1 抑制是否会影响脓毒症后 24 小时（第 2-3 年）离体心脏制剂中的心肌功能。 具体目的旨在评估脓毒症期间 ECE-1 抑制是否会抑制脓毒症引起的心肌功能障碍，其特征是 p38 MAPK 下调和 iNOS 蛋白表达抑制。具体目标的新颖之处在于，结果将为 ET-1 生物合成与心肌中 p38MAPK 和 iNOS 蛋白表达之间的因果关系提供证据。加深对脓毒症这两个阶段（脓毒症后 12 小时和 24 小时）的潜在机制的了解将有助于设计针对脓毒症早期和晚期阶段的治疗干预措施。