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

两个通道（电压依赖性L型CaD12+D1通道（VDCCs）和大电导CaD12+D1激活的KD1+D1通道（BKCs）的离子电流密度与其通道亚型（αiiD21cieD2亚基）mRNA表达水平之间的相互关系L型CaiiD12+ieD1通道数(α1C) 和 α/β 亚基 (αBK/βBK)) 在兔主动脉中的 BK 电流 (IiiD2K-CaieD2) 中测定，远小于兔输精管中的电流。 +dieD1 电流 (IiiD2CaieD2) 由 Bay K 8644 增加， IiiD2K-CaiiD2也显着增加，特别是在主动脉平滑肌细胞中，膀胱和输精管中编码α1C的mRNA含量明显高于主动脉和气管中，相反，编码αBK和βBK的mRNA含量。在他们的四种组织中观察到相似的水平，这些观察结果提出了 VDCC 和 BKC 的定量差异可能为膜差异提供解释的可能性。主动脉和气管与膀胱和输精管之间的兴奋性。在豚鼠平滑肌的皮纤维中检查了钌红（RuR）对收缩性的影响，RuR增强了膀胱皮纤维的收缩（ECiiD250 D2 = 60μM）。 pCa 6.0 时的收缩增加至对照的 320% 100μM RuR 在回肠纵向平滑肌层和肠系膜动脉中获得了相同的定性结果，RuR 的应用对 pCa 4.5 诱导的最大收缩没有显着影响，微囊藻毒素是一种有效的蛋白磷酸酶抑制剂，可诱导皮肤平滑肌的强直收缩。低 [CaiD12+IeD1] (pCa >8.0) 的肌肉对微囊藻毒素诱导的收缩：在低浓度下增强，在高浓度下抑制，[CaliD12+IeD1]从 pCa 5.0 降低至 >8.0 后，添加 RuR 可使 pCa 6.3 的肌球蛋白轻链磷酸化显着减慢。这些结果表明，RuR 至少部分通过抑制显着增加了收缩系统的 CaiD12+D1 敏感性。通过快速扫描共聚焦显微镜同时测量二维 CaiD12+D1 D1 图像和整体下的膜电流，分析了兔心房肌细胞中 CaiD12+D1 火花与瞬态 ClaiD1-D1 电流激活之间的时空关系。结果表明 D12+D1 火花启动。全局 [CaiD12+D1]D2iD2 的一些模式，并且 CaiD12+D1 热点或 CaiD12+D1 波是单个 Ca CaD12+D1 火花的时空总和，这导致 CaD12+D1 依赖离子通道的激活可以强烈建议在肌膜上。在兔心房肌细胞中，CaiD12+D1 火花不仅是兴奋-收缩 (E-C) 耦合的功能单位，而且也是激活 CaiD12+D1 依赖性膜电流（主要是 IiD2Cl-Ca D2）的功能单位。

项目成果

Aki Yamada et al.: "Ca^ 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。