大鼠新生心房肌细胞中的钙激活非选择性阳离子通道
Ca2+ -activated nonselective cation channels in rat neonatal atrial myocytes.
作者信息
Zhainazarov A B
机构信息
Department of Cardiology, Children's Hospital, 320 Longwood Avenue, Boston, MA 02115, USA.
出版信息
J Membr Biol. 2003 May 15;193(2):91-8. doi: 10.1007/s00232-002-2010-8.
A nonselective cation channel activated by intracellular Ca(2+) was identified in inside-out membrane patches taken from cultured rat atrial myocytes. Ca(2+) (0.01-1.00 m M) reversibly activated the channel in a concentration-dependent manner. The channel often showed a quick and irreversible rundown within a few minutes after patch excision. The I-V relationship of the channel was linear between -100 and +100 mV. The single channel conductance was 26.0 +/- 0.5 pS and its open probability was weakly voltage-dependent. Ion-substitution experiments showed that the channel was permeable to monovalent cations (P(x)/P(Cs): Li(+) (1.5) = K(+) (1.5) > Na(+) (1.2) > Rb(+) (1.1) > Cs(+) (1.0)) but not to Cl(-) (P(Cl)/P(Cs) < 0.01) and Ca(2+) (P(Ca)/P(Cs) = 0.02 +/- 0.01).
在取自培养的大鼠心房肌细胞的内面向外膜片上鉴定出一种由细胞内Ca(2+)激活的非选择性阳离子通道。Ca(2+)（0.01 - 1.00 mM）以浓度依赖性方式可逆地激活该通道。该通道在膜片钳切除后的几分钟内常常表现出快速且不可逆的电流衰减。该通道的电流-电压关系在-100至+100 mV之间呈线性。单通道电导为26.0±0.5 pS，其开放概率呈弱电压依赖性。离子置换实验表明，该通道对单价阳离子通透（P(x)/P(Cs)：Li(+)（1.5）= K(+)（1.5）> Na(+)（1.2）> Rb(+)（1.1）> Cs(+)（1.0）），但对Cl(-)不通透（P(Cl)/P(Cs) < 0.01），对Ca(2+)也不通透（P(Ca)/P(Cs) = 0.02±0.01）。
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