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

本研究进行了为期两年的“钙诱导的钙释放机制的心肌Ryanodine受体（RyR）的电生理学研究”项目，获得了以下结果。来自心脏RyR的单通道活性被重构为平面脂质双层。(1)我们探索了RyR通过磷酸化调节通道活性的机制。RyR被蛋白激酶A亚基激活。磷酸化RyR通道打开/关闭更频繁，保持打开更长时间，保持关闭更短时间。这一结果进一步证实了细胞对Mg ~（2+）胞浆封闭配体的敏感性降低是导致细胞活化的原因。关于这项工作的论文最近被Pflugers Archiv接受。(2)我们研究了另一种调制机制的通道活性的RyR的病理生理代谢物从膜脂质，如鞘脂。虽然这种物质是脂质，但它可能与通道分子的特异性胞质位点结合并阻断通道活性。关于这项工作的论文已经提交给了一些期刊。(3)我们还分析了RyR的真实的电流抑制Ca诱导的Ca释放的失活机制。因此，我们正在准备一份关于这项工作的论文，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Ca诱导的Ca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.