CARDIAC MYOCYTES CULTURED BEATING--IRON OVERLOAD MODEL

心肌毒性是最重要的限制生命的并发症 铁超载。心肌铁毒性的研究已受到重视 由于缺乏令人满意的实验模型而受阻。我们有 先前表明，培养的大鼠心肌细胞的铁负荷导致 异常的收缩和电生理行为并增加 膜脂过氧化，可通过去铁胺处理而逆转。在……里面 在我们下一阶段的研究中，我们打算澄清 膜脂结构的结构变化与功能 铁中毒引起的异常。这些研究将继续进行。 3条线：I.分离的类脂膜的结构变化 肌膜、线粒体和溶酶体的特征将通过测量 它们的磷脂、溶血磷脂、磷脂 乙醇胺/磷脂酰胆碱的含量，并通过识别膜 与外部环境直接接触的脂类部分和 可用于放射性碘标记或与 三硝基苯磺酸盐。细胞器功能异常 记录于(A)肌膜，通过测量跨膜电位和 钙摄取；(B)通过测量ADP刺激的线粒体和ADP- 限制呼吸和呼吸控制率，以及；(C)在溶酶体内 通过测量潜伏酸和可沉淀酸记录的它们的脆弱性 水解酶活性。抗坏血酸、α-生育酚、 低氧和去铁胺对铁诱导的修饰或预防 将对异常情况进行调查。细胞器功能异常会 与膜结构的改变相关。初级阶段 铁毒性的靶点将通过时间和程度来确定 在各种细胞器中观察到结构或功能异常 从富含铁的心脏细胞中提取。从这些文件中获得的信息 研究将有助于阐明心肌疾病的发病机制 在铁超载的情况下，缺氧、铁络合剂和 抗氧化剂可以改变或防止铁对心脏的损害，并且 可能有助于开发更合理和有效的方法来解决 输血铁超载的管理。

Myocardial toxicity is the most important life-limiting complication of iron overload. Research on myocardial iron toxicity has been seriously hindered by the lack of a satisfactory experimental model. We have previously shown that iron-loading of cultured rat heart cells results in abnormal contractility and electrophysiologic behaviour and increased peroxidation of membrane lipids, reversible by deferoxamine treatment. In the next phase of our studies we intend to clarify the relation between structural alterations in membrane lipid architecture and the functional abnormalities induced by iron toxicity. These studies will proceed along 3 lines: I. Structural changes in lipid membranes isolated from the sarcolemma, mitochondria and lysosomes will be characterized by measuring their phospholipid, lysophospholipid, phosphatidyl ethanolamine/phosphatidyl choline content, and by identifying membrane lipid moieties in direct contact with the external environment and accessible for radioiodinationor interaction with the with trinitrobenzene sulphonate. II. Abnormal organelle function will be documented in (a) the sarcolemma by measuring transmembrane potential and calcium uptake; (b) in mitochondria by measuring ADP-stimulated and ADP- limited respiration and respiratory control ratio, and; (c) in lysosomes by measuring their fragility documented by latent and sedimentable acid hydrolase activities. III. The ability of ascorbate, alpha-tocopherol, hypoxia and deferozamine to modify or prevent the iron-induced abnormalities will be explored. Abnormalities in organelle function will be correlated with alterations in membrane architecture. The primary target of iron toxicity will be identified by the timing and extent of structural or functional abnormalities observed in the various organelles obtained from iron loaded heart cells. Information gained in these studies will help in clarifying the pathogenesis of mypocardial disease in iron overload, the manner in which hypoxia, iron chelating agents and antioxidants may modify or prevent iron-induced damage to the heart, and may be useful in developing more rational and effective methods for the management of transfusional iron overload.