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Study on mechanism of modulation of cardiac L-type Ca^<2+> channel by phosphorylation and Ca^<2+>

磷酸化和Ca^<2>调节心脏L型Ca^<2>通道的机制研究

基本信息

批准号：
07457013
负责人：
OCHI Rikuo
金额：
$ 3.58万
依托单位：
Juntendo Universitv School of Medicine
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07457013/
关键词：
Ca^<2+> channel single channel gating process phoisphorylation isoproterenol BAY K 8644 antisence beta-subunit Ca培玩薬 Caアゴニスト

项目摘要

The major aim of the present study was to clarify the changes of the gating process of the cardiac L-type Ca^<2+> channels produced by channel phoisphorylation based on single channel analysis. During the course of the study, new problem of the involvement of Ca^<2+> channel beta-subunit on the phosphorylation-dependent modulation arised.Results1.Isoproterenolincreased mainly availability (Ps) and slightly openprobability (Po) of the L-type channel to increase the channel current. The increase of its concentration between 1 nM and 0.1 mM did not increase the rate of mode-2 sweeps.2.The rate of mode-2 sweeps in the presence of BAY K 8644 was significantly increased by isoproterenol.3.The time course of inactivation of macroscopic Ba^<2+> current was enhanced by nitrendipine and this was enhanced by isoproterenol.4.Treatment by beta-subunit antisence of cultured adult rabbit ventricular myocytes decreased the L-type current density by 30%, increased the time course of rise and decay of the current by a factor of two and significantly decreased the efficacy of isoproterenol to increase the current.Future prospectAccumulating knowledges from molecular biology study using heterologous expression system indicated the multisubuinit organization of L-type Ca^<2+> channels, phosphorylation sites in alpha-1 subunit and phosphorylation of beta subunit. Using antisence technology towards native cardiac myocytes and applying single channel recording technique we have a good chance to disclose the role of beta subunit in Ca^<2+> channel regulation.

本研究的主要目的是基于单通道分析阐明通道磷酸化产生的心脏L型Ca^2+通道门控过程的变化。在研究过程中，出现了Ca^2+通道β亚基参与磷酸化依赖性调节的新问题。结果1.异丙肾上腺素主要增加L型通道的可用性(Ps)和轻微开放概率(Po)，从而增加通道电流。其浓度在 1 nM 和 0.1 mM 之间增加并不会增加模式 2 扫描速率。2.异丙肾上腺素显着增加在 BAY K 8644 存在的情况下模式 2 扫描速率。3.宏观 Ba^<2+> 电流失活的时间进程被尼群地平增强，而异丙肾上腺素也增强这种情况。4.通过 β-亚基反义治疗培养的成年兔心室肌细胞使L型电流密度降低30%，电流上升和衰减的时间过程增加两倍，并显着降低异丙肾上腺素增加电流的功效。未来展望使用异源表达系统的分子生物学研究积累的知识表明L型Ca^2+通道的多亚单位组织， α-1 亚基的磷酸化位点和 β 亚基的磷酸化位点。利用针对天然心肌细胞的反义技术并应用单通道记录技术，我们有很好的机会揭示β亚基在Ca^2+通道调节中的作用。