CARDIAC TOXICITY OF PHOSPHOLIPID METABOLITES

描述：(改编自《调查者摘要》)。这样做的目的是 项目是研究磷脂代谢物，白毒素的作用 (Lx)和心脏中的白毒素二醇(Lx-diol)。白斑毒素是一种环氧化环。 亚油酸的衍生物，细胞膜的一种常见成分，由 严重烧伤患者和正常心肌缺血时的白细胞。 血浆LX水平与晚期多器官衰竭相关 在烧伤病人身上。其中一个后果是血管崩溃和心脏骤停。 最近，LX被证明能引起狗的心脏骤停。最近的实验 在培养的细胞模型中提出，要使LX具有细胞毒性，它必须 首先被可溶性环氧化物水解酶(SEH)代谢成LX-二醇。他们的 初步实验表明，在大鼠心脏，LX没有作用；然而， LX-Diol抑制心脏动作电位、钠电流和一过性 外向电流。这项研究将检验这一假说，即 LX的心脏毒性作用是LX被sEH代谢成LX-二醇，导致 它的激活。此外，LX-Diol的作用是通过以下途径实现的 膜内离子通道动力学性质的改进 与通道蛋白的相互作用。具体地说，调查人员将 测量LX和LX-Diol对心脏动作电位、钠、 钙、钾通道电流和钠钾泵电流。 对动作电位和膜电流的影响将被比较 大鼠、小鼠和豚鼠的心肌细胞，这些物种已知有 SEH具有不同的内在活性。被识别为正在被 LX-二醇或LX将进一步表征动力学和电压 依赖属性，以确定修改电流的机制。 分离的成人心肌细胞将作为模型系统来测试这一点 假设。全细胞膜片钳技术将用于测量动作 分离的心肌细胞的电势和离子电流。电流的结果 测量将被用来预测对完整心脏的影响 将通过乳头肌实验进行测试的肌肉。这样做的结果是 研究应证明sEH在LX毒性效应中的作用 化合物(LX或LX-二醇)对心脏有直接影响， 因此，可能对临床和临床上可见的心力衰竭负责 实验室里的动物。此外，这将为我们提供对 导致这种类型心力衰竭的机制。最后，他们将开始 了解这些化合物的作用机理。 心肌细胞的电生理特性。这一新证据将 更好地了解这些临床上重要的毒物，并可 为这些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.