Dihydropyridine-sensitive calcium channels expressed in canine colonic smooth muscle cells.
Dihydropyridine-sensitive calcium channels expressed in canine colonic smooth muscle cells.
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DOI：
10.1152/ajpcell.1993.264.3.c745
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发表时间：
1993-03
期刊：
影响因子：
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通讯作者：
A. Rich;J. L. Kenyon;J. Hume;K. Overturf;B. Horowitz;K. Sanders
中科院分区：
文献类型：
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作者：
A. Rich;J. L. Kenyon;J. Hume;K. Overturf;B. Horowitz;K. Sanders
进行实验来识别和表征调节犬结肠平滑肌内向钙电流的钙通道类型。使用来自犬近端结肠的环形层的新鲜分散的平滑肌细胞。使用 80 mM Ba2+ 作为电荷载体测量单通道电流。在正向-30 mV 的去极化电压阶跃期间，观察到小电导（10 +/- 2 pS，EBa = 46 +/- 11 mV，n = 9）和大电导（21 +/- 1 pS，EBa = 52 +/- 3 mV，n = 19）单通道电流。在浴液中添加10(-6) M硝苯地平可以抑制两种类型的单通道电流。较小的电流很少被观察到，因此没有进一步表征。较大电流幅度的开路概率 (P(o)) 强烈依赖于电压。玻尔兹曼函数很好地描述了激活曲线，半激活发生在 4 mV 处，膜电位增加 5 mV 导致 P(o) 增加 e 倍。 BAY K 8644 (1 microM) 使激活曲线向左移动，而硝苯地平 (1 microM) 则导致向右移动。分子分析表明，该组织中仅表达 Ca2+ 通道 α 1 亚基的 C 类。此外，仅观察到单个剪接变体（rbc-II）。结果表明，一类二氢吡啶敏感钙通道调节犬结肠平滑肌细胞中的内向钙电流。
Experiments were performed to identify and characterize the types of calcium channels that regulate inward calcium current in canine colonic smooth muscle. Freshly dispersed smooth muscle cells from the circular layer of the canine proximal colon were used. Single-channel currents were measured with 80 mM Ba2+ as the charge carrier. Small-conductance (10 +/- 2 pS, EBa = 46 +/- 11 mV, n = 9) and large-conductance (21 +/- 1 pS, EBa = 52 +/- 3 mV, n = 19) single-channel currents were observed during depolarizing voltage steps positive to -30 mV. Both types of single-channel currents were inhibited by the addition of 10(-6) M nifedipine to the bath solution. The smaller current was infrequently observed and therefore was not further characterized. Open probability (P(o)) of the larger current amplitude was strongly dependent on voltage. Activation curves were well described by a Boltzmann function with half activation occurring at 4 mV, and a 5-mV increase in membrane potential resulted in an e-fold increase in P(o). BAY K 8644 (1 microM) shifted the activation curve to the left while nifedipine (1 microM) resulted in a right shift. Molecular analysis showed that only the C class of Ca2+ channel alpha 1-subunit is expressed in this tissue. Furthermore, only a single splice variant (rbc-II) was observed. The results suggest that a single class of dihydropyridine-sensitive calcium channels regulates inward calcium current in canine colonic smooth muscle cells.