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首页> 外文期刊>Canadian Journal of Physiology and Pharmacology >Diversity of K+ channels in circular smooth muscle of opossum lower esophageal sphincter.
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Diversity of K+ channels in circular smooth muscle of opossum lower esophageal sphincter.

机译：负鼠食管括约肌圆形平滑肌中K +通道的多样性。

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摘要

We previously demonstrated that a balance of K+ and Ca2+-activated Cl- channel activity maintained the basal tone of circular smooth muscle of opossum lower esophageal sphincter (LES). In the current studies, the contribution of major K+ channels to the LES basal tone was investigated in circular smooth muscle of opossum LES in vitro. K+ channel activity was recorded in dispersed single cells at room temperature using patch-clamp recordings. Whole-cell patch-clamp recordings displayed an outward current beginning to activate at -60 mV by step test pulses lasting 400 ms (-120 mV to +100 mV) with increments of 20 mV from holding potential of -80 mV ([K+]I = 150 mM, [K+]o = 2.5 mM). However, no inward rectification was observed. The outward current peaked within 50 ms and showed little or no inactivation. It was significantly decreased by bath application of nifedipine, tetraethylammonium (TEA), 4-aminopyridine (4-AP), and iberiotoxin (IBTN). Further combination of TEA with 4-AP, nifedipine with 4-AP, and IBTN with TEA, or vice versa, blocked more than 90% of the outward current. Ca2+-sensitive single channels were recorded at asymetrical K+ gradients in cell-attached patch-clamp configurations (100.8+/-3.2 pS, n = 8). Open probability of the single channels recorded in inside-out patch-clamp configurations were greatly decreased by bath application of IBTN (100 nM) (Vh = -14.4+/-4.8 mV in control vs. 27.3+/-0.1 mV, n = 3, P < 0.05). These data suggest that large conductance Ca2+-activated K+ and delayed rectifier K+ channels contribute to the membrane potential, and thereby regulate the basal tone of opossum LES circular smooth muscle.
机译：我们先前证明，K +和Ca2 +激活的Cl-通道活性的平衡保持了负鼠食管括约肌（LES）圆形平滑肌的基调。在目前的研究中，在负鼠的圆形平滑肌中研究了主要的K +通道对LES基音的贡献。使用膜片钳记录在室温下在分散的单个细胞中记录K +通道活性。全细胞膜片钳记录显示，通过持续400 ms（-120 mV至+100 mV）的阶跃测试脉冲在-60 mV处开始激活的向外电流，从-80 mV（[K +]的保持电势递增20 mV I = 150 mM，[K +] o = 2.5 mM。但是，没有观察到向内矫正。向外电流在50毫秒内达到峰值，几乎没有灭活或没有灭活。硝苯地平，四乙铵（TEA），4-氨基吡啶（4-AP）和埃博毒素（IBTN）的沐浴可显着降低其含量。 TEA与4-AP的进一步结合，硝苯地平与4-AP的结合以及IBTN与TEA的结合（反之亦然）阻止了超过90％的流出电流。 Ca2 +敏感的单通道以非对称K +梯度记录在细胞附着的膜片钳配置中（100.8 +/- 3.2 pS，n = 8）。通过浴液应用IBTN（100 nM），大大减少了由内而外的膜片钳配置中记录的单通道的打开概率（Vh = -14.4 +/- 4.8 mV，对照组为27.3 +/- 0.1 mV，n = 3，P <0.05）。这些数据表明，大电导的Ca2 +激活的K +和延迟的整流器K +通道有助于膜电位，从而调节负鼠LES圆形平滑肌的基调。

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