CULTURED CARDIAC MYOCYTES--A MODEL OF IRON OVERLOAD

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一直受到重视 由于缺乏令人满意的实验模型而受阻。我们有 先前表明，培养的大鼠心脏细胞的铁负荷导致 收缩力和电生理行为异常， 膜脂过氧化，可通过去铁胺处理逆转。在 我们的研究的下一个阶段，我们打算澄清之间的关系， 膜脂质结构的结构改变和功能改变 铁中毒引起的异常。这些研究将沿着进行 3条线：I.分离的脂质膜的结构变化 肌膜、线粒体和溶酶体将通过测量 它们的磷脂、溶血磷脂、磷脂酰 乙醇胺/磷脂酰胆碱含量，并通过鉴定膜 与外部环境直接接触的脂质部分， 可用于放射性碘化或与 三硝基苯磺酸盐二.异常的细胞器功能 （a）通过测量跨膜电位记录在肌膜中， 钙摄取;（B）通过测量ADP刺激的和ADP刺激的线粒体中的钙摄取; 有限的呼吸和呼吸控制比，和;（c）在溶酶体中 通过测量它们的脆弱性， 水解酶活性三.抗坏血酸，α-生育酚， 缺氧和去铁扎明，以修改或防止铁诱导的 将探索异常。细胞器功能的丧失将 与膜结构的改变有关。主 铁毒性的目标将通过时间和程度来确定， 在各种细胞器中观察到的结构或功能异常 从铁负载的心脏细胞获得。在这些方面获得的信息 研究将有助于阐明近视病的发病机制， 在铁超载中，缺氧、铁螯合剂和 抗氧化剂可以改变或防止铁引起的心脏损伤， 可能有助于发展更合理和有效的方法， 输血性铁超载的管理。

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.