ADULT MAMMALIAN CARDIAC MYOCYTES

我们计划扩展为分散而开发的方法 从大鼠、豚鼠和青蛙的单个心肌细胞到更大的物种， 此外，还研究了人心脏的某些特性， 将检查肌细胞。 心肌细胞会急剧分散 使用酶促解离方法。 一个严格的评估程序 该方法的成功已经确立，包括测量 超微结构、生化行为和电生理特性。 广泛的物种代表性的有用性源于这样一个事实， 每个物种都有其独特的优势。 例如，狗是最喜欢的 制备心脏肌膜，兔可用于起搏器研究， 大鼠提供了许多心脏病的遗传模型，青蛙没有t-小管 此外，还增强了结果的通用性 使用我们的方法。 将评价的细胞参数包括Ca 耐受性，心肌细胞超微结构，电生理特性 包括电缆特性、静息电位、膜电压和 配体门控电流，收缩活性，离子含量，离子通量， 线粒体功能、肌膜结合和环核苷酸 生产 将进行复溶实验，其中单个 通过膜片钳分离来自富含脂质的SL囊泡的通道。 钙通道将被研究，特别是从的角度来看， 二氢吡啶类，一类新的重要的钙通道调节剂。 这些 药物具有激动剂和拮抗剂作用，是高度有效的， 特定. 这些试剂与肌膜Ca通道的结合将是 与从单通道和整体测量的功能效应相比， 细胞电流 将特别注意依赖于状态的 约束力 家兔起搏电位下的电流 将检查起搏器和辅助起搏器组织， 将根据这些发现对起搏潜力进行评估。 自主神经递质、腺苷和ATP对起搏的影响 也将被审查。

We plan to extend methods that have been developed for the dispersion of single cardiac myocytes in rat, guinea pig and frog to larger species such as dog, rabbit and cat. In addition some properties of human cardiac myocytes will be examined. Cardiac myocytes will be dispersed acutely using enzymatic methods of dissociation. A rigorous program for evaluting the success of the method has been established and includes measurements of ultrastructure, biochemical behaviour and electrophysiological properties. The usefulness of a wide species representation arises from the fact that each species has special advantages. For example, dog is a favorite preparation for cardiac sarcolemma, rabbit is useful for pacemaker studies, rat provides many genetic models of cardiac disease, frog has no t-tubule system, etc. In addition, the generalizibility of results is enhanced using our approach. Cellular parameters that will be evaluated include Ca tolerance, myocyte ultrastructure, electrophysiological properties including cable properties, resting potential, membrane voltage and ligan-gated current, contractile activity, ion content, ion fluxes, mitochondrial function, sarcolemmal binding and cyclic nucleotide production. Reconstitution experiments will be done in which single channels from lipid-enriched SL vesicles are isolated by patch clamp. Calcium channels will be studied particularly from the point of view of the dihydropyridines, a new important class of Ca channel modulators. These agents have agonist and antagonist effects, are highly potent and very specific. The binding of these agents to sarcolemmal Ca channels will be compared to the functional effects measured from single channel and whole cell currents. Particular attention will be paid to state-dependent binding. The currents underlying the pacemaker potentials in rabbit pacemaker and subsidiary pacemaker tissue will be examined and a synthesis of the pacemaking potential in the light of these findings will be made. The effects of autonomic transmitters, adenosine, and ATP on pacemaking will also be examined.