CARDIAC TOXICITY OF PHOSPHOLIPID METABOLITES

描述：（改编自研究者摘要）。这个目标 项目是研究磷脂代谢物白细胞毒素的作用 (Lx)和心脏中的白细胞毒素二醇（Lx-diol）。白细胞毒素是一种环氧环 亚油酸的衍生物，是细胞膜的常见成分，由 严重烧伤患者和正常心肌缺血时的白细胞。 Lx的血浆水平与晚期多器官衰竭相关 烧伤患者中。一个后果是血管塌陷和心脏骤停。 最近，Lx已被证明会导致狗的心脏骤停。最近的实验 在培养的细胞模型中，已经表明Lx具有细胞毒性，它必须 首先通过可溶性环氧化物水解酶（sEH）代谢为Lx-二醇。他们的 初步实验表明，在大鼠心脏中，Lx没有影响;然而， LX-二醇抑制心脏动作电位、钠电流和瞬时 外向电流本研究将验证这一假设，即 Lx的心脏毒性作用是Lx被sEH代谢为Lx-二醇， 其激活。此外，LX-二醇的作用是通过以下途径介导的： 通过膜内改变离子通道的动力学性质 与通道蛋白的相互作用。具体而言，调查人员将 测量Lx和Lx-二醇对心脏动作电位、钠、 钙和钾通道电流和钠钾泵电流。 对动作电位和膜电流的影响将比较 大鼠、小鼠和豚鼠肌细胞，因为这些物种已知具有 sEH的不同内在活性。被确定为被改变的电流 Lx-二醇或Lx将进一步表征为动力学和电压 依赖的属性来确定电流被修改的机制。 分离的成年心肌细胞将被用作模型系统来测试这一点 假说.全细胞膜片钳技术将用于测量动作 分离的肌细胞中的电位和离子电流。当前结果 测量结果将用于预测对完整心脏的影响。 将用乳头肌实验测试的肌肉。成果 研究应证明sEH在Lx毒性作用中的作用， 化合物（Lx或Lx-二醇）对心脏具有直接作用， 因此，可能是导致临床和 实验室动物此外，这将提供新的见解， 导致这种心力衰竭的机制。最后，他们将开始 为了了解这些化合物在改变 心肌细胞的电生理特性。新证据将 更好地了解这些临床上重要的毒物， 为此类患者的合理治疗提供依据。

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.