CARDIAC TOXICITY OF PHOSPHOLIPID METABOLITES

磷脂代谢物的心脏毒性

• 批准号: 6184172
• 负责人: JOSEPH R STIMERS
• 金额: $ 22.02万
• 依托单位: UNIV OF ARKANSAS FOR MED SCIS
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-08-01 至 2002-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6184172
• 关键词: calcium channel; cardiotoxin; epoxide hydrolase; guinea pigs; heart disorder; heart electrical activity; laboratory mouse; laboratory rat; linoleate; lipid metabolism; membrane potentials; pathologic process; phospholipids; potassium channel; sodium channel; voltage /patch clamp

DESCRIPTION: (Adapted from the Investigator's Abstract). The goal of this project is to investigate the role of the phospholipid metabolites, leukotoxin (Lx), and leukotoxin-diol (Lx-diol) in the heart. Leukotoxin is an epoxide ring derivative of linoleic acid, a common component of cell membranes, formed by leukocytes in severely burned patients and during normal myocardial ischemia. Plasma levels of Lx have been correlated with late stage multiple organ failure in burn patients. One consequence is vascular collapse and cardiac arrest. Recently, Lx has been shown to cause cardiac arrest in dogs. Recent experiments in a cultured cell model have suggested that for Lx to be cytotoxic, it must first be metabolised to Lx-diol by a soluble epoxide hydrolase (sEH). Their preliminary experiments show that, in rat heart, Lx is without effect; however, Lx-diol suppresses the cardiac action potential, sodium current and transient outward current. This study will test the hypothesis that the mechanism of cardiotoxic effects of Lx is that Lx is metabolized by sEH to Lx-diol, causing its activation. Furthermore, the effects of Lx-diol are mediated by modification of kinetic properties of ion channels through intramembrane interactions with channel proteins. Specifically, the investigators will measure effects of Lx and Lx-diol on the cardiac action potential, sodium, calcium, and potassium channel currents and sodium potassium pump current. Effects on the action potential and membrane currents will be compared between rat, mouse, and guinea pig myocytes, as these species are known to have different intrinsic activities of sEH. Currents identified as being altered by either Lx-diol or Lx will be further characterized as to kinetic and voltage dependent properties to determine the mechanism by which currents are modified. Isolated adult cardiac myocytes will be used as the model system to test this hypothesis. Whole cell patch clamp techniques will be used to measure action potential and ionic currents in the isolated myocytes. Results of current measurements will be used to make predictions on effects in intact cardiac muscle that will be tested with papillary muscle experiments. Results of this study should demonstrate the role of sEH in toxic effects of Lx in which compounds (Lx or Lx-diol) is having a direct effect on the heart and, therefore, may be responsible for the heart failure seen both clinically and in the laboratory animals. Furthermore, this will provide new insights into the mechanisms responsible for this type of heart failure. Finally, they will begin to understand the mechanism of action of these compounds in altering electrophysiological properties of cardiac myocytes. This new evidence will provide a better understanding of these clinically important toxicants and may provide the basis for rationale treatment of these patients.

描述：（根据研究者的摘要进行了改编）。目标的目标 项目是研究磷脂代谢产物白细胞毒素的作用 （LX）和心脏中的白细胞毒素二醇（LX-二醇）。白细胞毒素是环氧环 亚油酸的衍生物是细胞膜的常见成分，由 严重燃烧的患者和正常心肌缺血期间的白细胞。 LX的血浆水平与后期多器官衰竭相关 在燃烧的患者中。结果之一是血管塌陷和心脏骤停。 最近，LX已被证明会导致狗心脏骤停。最近的实验 在培养的细胞模型中，LX具有细胞毒性，必须 首先通过可溶性环氧水解酶（SEH）代谢为LX-二醇。他们的 初步实验表明，在大鼠心脏中，LX无效。然而， LX二醇抑制心脏作用电位，钠电流和瞬态 向外电流。这项研究将检验以下假设 LX的心脏毒性作用是LX被SEH代谢至LX-二醇，导致 它的激活。此外，LX-二醇的作用是由 通过膜内的离子通道的动力学特性修饰 与通道蛋白的相互作用。具体来说，调查人员将 测量LX和LX-二醇对心脏作用电位的影响，钠， 钙，钾通道电流和钠钾泵电流。 将比较对动作电位和膜电流的影响 老鼠，小鼠和豚鼠肌细胞，因为已知这些物种具有 SEH的不同内在活动。电流被确定为被改变 LX-二醇或LX将进一步表征有关动力学和电压 依赖性属性，以确定经电流修改的机制。 孤立的成人心肌细胞将用作模型系统进行测试 假设。全细胞贴片夹技术将用于测量动作 分离的肌细胞中的潜在和离子电流。电流的结果 测量将用于对完整心脏的影响进行预测 将通过乳头肌肉实验进行测试的肌肉。结果 研究应证明SEH在LX的毒性作用中的作用 化合物（LX或LX-二醇）对心脏有直接影响，并且 因此，可能导致临床和中看到的心力衰竭 实验动物。此外，这将为您提供新的见解 导致这种类型心力衰竭的机制。最后，他们将开始 了解这些化合物在改变时的作用机理 心肌细胞的电生理特性。这个新证据将 对这些临床上重要的毒物有更好的了解，可能 为这些患者的理由治疗提供了基础。