Characterization of the bi-directional communication between the ryanodine receptor (RyR) and the dihydropyridine receptor (DHPR) in skeletal muscle.

骨骼肌中兰尼碱受体 (RyR) 和二氢吡啶受体 (DHPR) 之间双向通讯的表征。

基本信息

批准号：
13670098
负责人：
SUDA Norio
金额：
$ 1.28万
依托单位：
Jikei University School of Medicine
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

This project was conducted to characterize bi-directional communications between the SR membrane and the T-tubule membrane.1) Orthograde signal from the DHPR to the RyR : Application of caffeine, a potentiator of Ca^<2+>-induced Ca^<2+> release (CICR), induces continuous release of Ca^<2+> from the SR (caffeine-contracture). When a sustained depolarization is applied during the caffeine-contracture, subsequent repolarization terminates Ca^<2+> release (RISC : PNAS91, 5725, 1994). Because caffeine failed to induce Ca^<2+> release following the depolarizing pulse, it is strongly suggested that CIOR is inhibited at a time ofrepolarization. RISC was absent in dysgenic (DHPR-lacking) mouse myotubes, although expression of the skeletal DHPR in dysgenic myotubes restored RISC, suggesting involvement of the skeletal DH PR in RISC. CICR induced by caffeine was also terminated following the cessation of repetitive field stimulation (20Hz) applied on top of caffeine-contracture. Electron -microscopy revealed that inmyoballs, obtained by colchicines treatment, SR membranes and T-tubule membranes were located in closeproximity with each other.2) Retrograde signal from the SR to the plasma (T-tubule) membrane : When rat myotubes, pretreated with SR Ca^<2+> pump inhibitors (e.g.TG), were exposed to caffeine (10mM), the cells showed an increase in cytoplasmic Ca^<2+> concentration, due presumably to Ca^<2+> entry from the extracellular space. We also found a novel pathway for Ca^<2+> entry activated at the resting membrane potential in rat skeletal myotubes. This Ca^<2+> entry was present in dysgenic myotubes. We are now investigating whether the novel Ca^<2+> entry is regulated by SR Ca^<2+> content or the state of the RyR.

该项目的进行表征是为了表征SR膜和T-pubule膜之间的双向通信。1）从DHPR到RYR到RYR的正流信号：咖啡因的应用，Ca^<2+> - 诱导的Ca^<2+>释放（CICR）的增强剂，ca^<2+> con（con）持续释放。当在咖啡因合同期间施加持续的去极化时，随后的重极化终止Ca^<2+>释放（RISC：PNAS91，5725，1994）。由于咖啡因在去极化脉冲后未能诱导Ca^<2+>释放，因此强烈建议在旋转时抑制Cior。尽管骨骼DHPR的表达恢复了RISC，但RISC不存在于骨骼DHPR的表达，但不存在RISC，尽管骨骼DHPR的表达恢复了RISC，这表明骨骼DH PR参与了RISC。在停止在咖啡因合同顶部施加的重复场刺激（20Hz）之后，咖啡因诱导的CICR也终止。电子 - 微观镜检查表明，通过秋水仙碱处理，SR膜和T纤维膜获得的Inmyoballs彼此之间的近距离近克度位置。咖啡因（10mm），细胞显示出细胞质Ca^<2+>浓度的增加，这可能是由于Ca^<2+>从细胞外空间进入。我们还发现了在大鼠骨骼肌管中静止膜电位激活的Ca^<2+>进入的新途径。此Ca^<2+>进入失调肌管中。我们现在正在研究新颖的Ca^<2+>输入是由Sr Ca^<2+>含量或RYR的状态调节的。