EXPRESSION OF IONIC CHANNELS DURING CARDIOVASCULAR DISEASE

心血管疾病期间离子通道的表达

• 批准号: 10044313
• 负责人: IMAIZUMI Yuji
• 金额: $ 2.75万
• 依托单位: NAGOYA CITY UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B).
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10044313/
• 关键词: smooth muscle; CaィイD12+ィエD1 activated KィイD1+ィエD1 channel; L-type CaィイD12+ィエD1 channel; CaィイD12+ィエD1 spark; CaィイD12+ィエD1-activated ClィイD1-ィエD1 current; CaィイD12+ィエD1-induced CaィイD12+ィエD1 release; cardiac atrial myocyte; ruthenium red; 負帰還機構; Ca依存性K

The interrelationship between the ionic current density of two channels (voltage-dependent L-type CaィイD12+ィエD1 channels (VDCCs) and large conductance CaィイD12+ィエD1 activated KィイD1+ィエD1 channels (BKCs) and the mRNA expression level of their channel subtypes (αィイD21cィエD2 subunit of L-type CaィイD12+ィエD1 channels (α1C) and α/β subunits of BK channel (αBK/βBK)) was determined in rabbit smooth muscles. BK currents (IィイD2K-CaィエD2) in the rabbit aorta were much smaller than those in the rabbit vas deferens. However, when CaィイD12+ィエD1 current (IィイD2CaィエD2) was increased by Bay K 8644, IィイD2K-CaィエD2 was also markedly increased especially in aortic smooth muscle cells. The amount of mRNA contents of encoding α1C was apparently higher in urinary bladder and vas deferens than that in aorta and trachea. In contrast, the mRNA contents of encoding both αBK and βBK were observed at similar levels in their four tissues. These observation raised the possibility that quantitative differences in the VDCC and … More BKC may provide an explanation for the differences in membrane excitability between aorta and trachea versus urinary bladder and vas deferens.The effects of ruthenium red (RuR) on contractility were examined in skinned fibers of guinea pig smooth muscles. Contractions of skinned fibers of the urinary bladder were enhanced by RuR (ECィイD250ィエD2=60μM). The contraction at pCa 6.0 was increased to 320% of control by 100μM RuR. Qualitatively the same results were obtained in the ileal longitudinal smooth muscle layer and mesenteric artery. Maximal contraction induced by pCa 4.5 was not affected significantly by RuR. Application of microcystin, a potent protein phosphatase inhibitor, induced a tonic contraction of skinned smooth muscle at low [CaィイD12+ィエD1] (pCa >8.0). RuR had a dual effect on the microcystin-induced contraction : enhancement at low concentrations and suppression at high concentrations. The relaxation following the decrease in [CaィイD12+ィエD1] from pCa 5.0 to >8.0 was significantly slowed down by an addition of RuR. Phosphorylation of myosin light chain at pCa 6.3 was significantly increased by RuR. These results indicate that RuR markedly increases CaィイD12+ィエD1 sensitivity of the contractile system at least in part via inhibition of myosin light chain phosphatase.Spatiotemporal relationships between CaィイD12+ィエD1 sparks and the activation of transient ClィイD1-ィエD1 current were analyzed in rabbit atrial myocytes based on simultaneous measurements of two dimensional CaィイD12+ィエD1 images by fast scanning confocal microscopy and membrane currents under whole cell voltage-clamp. The results suggest that CaィイD12+ィエD1 sparks initiate some patterns of global [CaィイD12+ィエD1]ィイD2iィエD2, and that either a CaィイD12+ィエD1 hot spot or a CaィイD12+ィエD1 wave is the spatiotemporal summation of individual CaィイD12+ィエD1 sparks, which results in the activation of CaィイD12+ィエD1 dependent ion channels on the sarcolemma. It can be strongly suggested that a CaィイD12+ィエD1 spark is a functional unit not only in excitation-contraction (E-C) coupling but also in the activation of CaィイD12+ィエD1 dependent membrane current, mainly IィイD2Cl-CaィエD2, in rabbit atrial myocytes. Less

本实验测定了两种通道(电压依赖性L型钙ィイD12+ィエD1通道(VDCC)和大电导CaィイD12+ィエD1激活的KィイD1+ィエD1通道(BKCs))的离子电流密度与其通道亚型(αィイD21CィエD2 L钙通道ィイD12+ィエD1亚基(α1C)和BK通道α/β亚基(αBK/βBK))基因表达水平的相互关系。兔主动脉的BK电流(Iィイ、D2K-Ca、ィエ、D2)明显小于输精管。然而，当BAY K8644增加CaィイD12+ィエD1电流(IィイD2CaィエD2)时，IィイD2K-CaィエD2也显著增加，尤其是在主动脉平滑肌细胞上。α1C编码基因在膀胱和输精管中的含量明显高于主动脉和气管。而编码α-BK和β-BK的基因在四种组织中的表达水平基本相同。这些观察结果提出了VDCC和…之间的数量差异更多的BKC可能为主动脉和气管与膀胱和输精管之间的膜兴奋性差异提供了解释。在豚鼠的皮肤平滑肌纤维上观察了Ru红(RUR)对收缩的影响。RUR(ECィイD250ィエD2=60μM)可增强膀胱皮肤纤维的收缩。100μM RUR使PCA6.0的收缩增加到对照的320%。在回肠纵行肌层和肠系膜动脉中也有相同的结果。RUR对PCA4.5诱发的最大收缩无明显影响。应用一种有效的蛋白磷酸酶抑制剂微囊藻毒素，可在低[CaィイD12+ィエD1]条件下引起皮肤平滑肌紧张性收缩(Pca&gt；8.0)。RUR对微囊藻毒素诱导的收缩具有双重作用：低浓度时增强，高浓度时抑制。随着[CaィイD12+ィエD1]从PCA5.0下降到&gt；8.0，RUR的加入显著减缓了松弛的速度。RUR可显著提高PCA6.3位肌球蛋白轻链的磷酸化水平。这些结果表明，RUR至少部分通过抑制肌球蛋白轻链磷酸酶而显著增加收缩系统对CaィイD12+ィエD1的敏感性。基于快速扫描共聚焦显微镜二维图像和全细胞电压钳下膜电流的同步测量，分析了心房肌细胞CaィイD12+ィエD1火花与瞬时氯ィイD1-ィエD1电流激活的时空关系。结果提示，CaィイD12+ィエD1火花启动了整体的[CaィイD12+ィエD1]ィイD2iィエD2模式，而CaィイD12+ィエD1热点或CaィイD12+ィエD1波是单个CaィイD12+ィエD1火花的时空总和，导致肌膜上依赖于CaィイD12+ィエD1的离子通道的激活。结果表明，钙ィイD12+ィエD1火花不仅参与兴奋-收缩(E-C)偶联，而且激活依赖于钙ィイD12+ィエD1的膜电流，主要是IィイD2Cl-CaィエD2。较少

项目成果

Aki Yamada et al.: "Ca^<2+> sensitization of smoth musdo arttactility induced by ruthenium med"American Journal of Phystology. 276. C566-C575 (1999)

Aki Yamada 等人：“Ca ^ 2 > 钌引起的平滑肌触感的敏化”美国植物学杂志。