Electrophysiologicalestudy on the cardiac ryanodine receptor operating the Ca-induced Ca-release mechanisms.

在为期两年的“心脏兰尼定受体(RyR)调控钙释放机制的电生理学研究”项目中，我们获得了以下结果。心脏RyR的单通道活性被重组为平面脂质双层。(1)我们探索了一种通过磷酸化调节RyR通道活性的机制。RyR被蛋白激酶A亚基激活。磷酸化的RyR通道开放/关闭的频率更高，开放的时间更长，关闭的时间更短。结果表明，这种激活可归因于细胞内镁离子阻断剂敏感性的降低。我们研究了鞘磷脂等膜脂类的病理生理代谢物对RyR通道活性的另一种调控机制。虽然这种物质是脂类物质，但它很可能结合到通道分子的特定细胞质位置，并阻断通道的活动。我们还分析了RyR真实电流抑制钙诱导的钙释放的失活机制。我们正在准备一篇关于这项工作的论文，从而阐明了心肌细胞胞质代谢产物对RyR的一些新的调节机制，RyR在钙诱导的钙释放中发挥着核心作用。

Performing the two-year project on "Electrophysiological study on the cardiac ryanodine receptor (RyR) operating the Ca-induced Ca-release mechanisms", we obtained the following results. The single-channel activity from the cardiac RyR was reconstituted into planar lipid bilayers.(1) We explored a modulation mechanism of the channel activity of the RyR via a phosphorylation. The RyR was activated by the protein kinase A subunit. The phosphorylated RyR channels open/close more frequently, stay open longer, stay closed for shorter periods. It was improved that the activation is ascribable to the decrease in sensitivity to the cytosolic blocking ligarid of Mg ion. A paper on this work was recently accepted by Pflugers Archiv.(2) We investigated another modulation mechanism of the channel activity of the RyR by the pathophysiological metabolytes from membrane lipids such as sphingolipids. Although this substance is lipid, it is likely to bind to the specific cytoplasmic site of the channel molecule and to block the channel activity. A paper on this work was already submitted to some journal.(3) We also analysed the inactivation mechanism of the real current of the RyR to inhibit the Ca-induced Ca-release. We are now preparing a paper on this work.Thus, some novel regulation mechanisms by cytoplasmic metabolites of the cardiac myocytes on RyR which exerts a central role of the Ca-induced Ca release have been elucidated.