Planar lipid bilayr and patch clamp studies on the single channel currents of cardiac sarcop lasmic reticulum.

心肌质网单通道电流的平面脂质双层和膜片钳研究。

• 批准号: 03670067
• 负责人: UEHARA Akira
• 金额: $ 1.28万
• 依托单位: Fukuoka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1992
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03670067/
• 关键词: Heart; Sarcoplasmic Reticulum; Ion Channels

Article 1 The effects of low (pCa 7.5 to 3) concentrations of intracellular calcium ion on a single potassium channel in the sarcoplasmic reticulum of canine heart ventricular muscle were investigated using a planar lipid bilayr technique. The low concentrations were obtained by mixing EGTA and calcium chloride. By varying the pCa of the cytoplasmic face between 3 to 7.5, two novel effects were observed. First, an increase in the intracellular Ca^<2+> concentration produced an increase in the unit current amplitude of open states ; the voltage-current relationship was ohmic at these concentrations. Second, an increase in the Ca^<2+> concentration increased the open probability. Both these effects of Ca^<2+> were dose-dependent, and were consistently observed in all channels tested. Thus, the SR potassium channel observed appears to belong to the class of Ca^<2+>-activated potassium channels.Article2 The modulating effects of Ca^<2+> on single K^+ channel currents in canine heart sarcop … More lasmic reticulum were studied using a planar lipid bilayr technique. The open-state probability and the unitary open-state current both decreased gradually as the Ca^<2+> concentration was reduced from pCa 3 to pCa 7.5. Each single-channel I-V curve was ohmic at any pCa : the modulating effect of Ca^<2+> within this range was voltage independent. The Ca^<2+> dose-response curves for the conductances and open probabilities were all biphasic in shape for both sides of the channel at the voltages used. However, Ca^<2+> within the pCa ranges used caused significantly more prominent activation of conductance and gating properties on the cytoplasmic side than it did on the SR luminal side. Furthermore, conductance decreased when cytoplasmic Ca^<2+> concentrations were greater than pCa 3. The I-V relation in this instance exhibited inward rectification caused by a voltage-dependent fast block. This suggests than cardiac SR K^+ channel currents may be activated or inhibited through various types Ca^<2+> binding sites on and within the channels. Less

第一条应用平面脂质双层膜技术研究了低浓度（pCa7.5 ~ 3）细胞内钙离子对犬心肌肌浆网钾通道的影响。通过混合EGTA和氯化钙获得低浓度。通过在3至7.5之间改变胞质面的pCa，观察到两种新的效应。首先，细胞内Ca^<2+>浓度的增加导致开放状态的单位电流幅度增加;在这些浓度下，电压-电流关系是欧姆的。第二，Ca^<2+>浓度的增加增加了开放概率。Ca^<2+>的这两种效应都是剂量依赖性的，并且在所有测试的通道中都能观察到。因此，所观察到的SR钾通道似乎属于Ca^<2+>激活的钾通道。第二章Ca^<2+>对犬心肌细胞单个K^+通道电流的调节作用 ...更多信息 用平面脂质双层技术研究了内质网。随着Ca^2+浓度从pCa 3降低到pCa 7.5，开放态概率和单位开放态电流均逐渐降低。每个单通道I-V曲线在任何pCa下都是欧姆性的：在这个范围内，Ca^2+的调节作用与电压无关。在所使用的电压下，通道两侧的电导和开放概率的Ca^2+剂量响应曲线都是双相的。然而，在所用pCa范围内的Ca^2+在胞质侧引起的电导和门控特性的激活比在SR腔侧显著更显著。此外，当胞质Ca^<2+>浓度大于pCa 3时，电导率下降.在这种情况下，I-V关系表现出由电压依赖性快速阻滞引起的内向整流。这表明心脏SR K^+通道电流可能通过通道上和通道内的各种Ca^2+结合位点被激活或抑制。少

项目成果

A.Uehara,M.Yasukohchi,S.Ogata and I.Imanaga: "Calcium modulation of single SR potassium channel currents in heart muscle" Pflugers Arch. (1992)

A.Uehara、M.Yasukohchi、S.Ogata 和 I.Imanaga：“心肌中单 SR 钾通道电流的钙调制”Pflugers Arch。

Uehara,A.: "Activation by intracellular calcium of a potassium channel in cardiac sarcoplasmic reticumlum." PflugersArch.417. 651-653 (1991)

Uehara,A.：“心脏肌浆网钾通道的细胞内钙激活。”

Uehara, A.: "Activation by intracellular calcium of a potassium channel in cardiac sarcoplasmic reticulum." Pflugers Arch. 417. 651-653 (1991)

Uehara, A.：“心脏肌浆网中钾通道的细胞内钙激活。”

Uehara,A.: "Calcium modulation of single SR potassium channel currents in heart muscle." J.Mol.Cell.Cardiol.25(In press). (1994)

Uehara,A.：“心肌中单个 SR 钾通道电流的钙调节。”