Functional and molecular identification of pH-sensitive K+ channels in murine urinary bladder smooth muscle
Functional and molecular identification of pH-sensitive K+ channels in murine urinary bladder smooth muscle
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DOI：
10.1111/j.1464-410x.2008.07541.x
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发表时间：
2008-07-01
影响因子：
4.5
通讯作者：
Koh, Sang Don
中科院分区：
文献类型：
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作者：
Beckett, Elizabeth A. H.;Han, Insoo;Koh, Sang Don
为了检查 pH 敏感的 K+ 通道在设置小鼠膀胱平滑肌静息膜电位中的作用，因为膀胱收缩性受到静息膜电位的影响，而静息膜电位主要受背景 K+ 电导调节。使用传统的微电极记录、等长张力测量、膜片钳记录、逆转录聚合酶链反应 (RT-PCR)、蛋白质印迹和免疫组织化学，我们评估了膀胱平滑肌细胞和组织。酸性 pH (pH 6.5)使小鼠膀胱平滑肌的静息膜电位去极化，并增加肌张力和收缩力。神经元阻滞剂或经典 K+ 通道拮抗剂不能消除 pH 引起的变化。利多卡因(1mm)和布比卡因(100μm)模拟了酸化外部溶液的效果，并且在利多卡因存在的情况下，通过将pH降低至6.5，不会引起收缩性的进一步增加。对新鲜分散的膀胱肌细胞进行电压钳实验表明，pH 6.5 会降低外向电流。用经典的 K+ 拮抗剂四乙铵 (10 mm)、4-氨基吡啶 (5 mm)、格列本脲 (10 μm) 或 apamin (300 nm) 预处理膀胱肌细胞不会抑制低 pH 对外向电流的影响。然而，利多卡因 (1 mm) 处理消除了酸性 pH 值对外向电流的影响。 RT-PCR 显示小鼠膀胱中酸敏感 K+ 通道 (TASK)-1 和 TASK-2 基因转录本的表达，免疫组织化学和蛋白质印迹分析显示 TASK-1 和 TASK-2 通道在平滑肌组织和细胞中表达和分布。 TASK 通道在膀胱平滑肌中表达，并有助于负责静息膜电位的基础 K+ 电导。
To examine the role of pH-sensitive K+ channels in setting the resting membrane potential in murine bladder smooth muscle, as bladder contractility is influenced by the resting membrane potential, which is mainly regulated by background K+ conductances.Using conventional microelectrode recordings, isometric tension measurements, patch-clamp recordings, reverse transcription-polymerase chain reaction (RT-PCR), Western blotting and immunohistochemistry, we assessed bladder smooth muscle cells and tissues.Acidic pH (pH 6.5) depolarized the resting membrane potential of murine bladder smooth muscles and increased muscle tone and contractility. The pH-induced changes were not abolished by neuronal blockers or classical K+-channel antagonists. Lidocaine (1 mm) and bupivacaine (100 mu m) mimicked the effects of acidifying the external solution, and in the presence of lidocaine no further increase in contractility was induced by reducing the pH to 6.5. Voltage-clamp experiments on freshly dispersed bladder myocytes showed that pH 6.5 decreased the outward current. Pre-treatment of bladder myocytes with the classical K+ antagonists tetraethylammonium (10 mm), 4-aminopyridine (5 mm), glibenclamide (10 mu m) or apamin (300 nm) did not inhibit the effects of low pH on outward current. However, treatment with lidocaine (1 mm) abolished the effects of acidic pH on outward current. RT-PCR showed the expression of the acid-sensitive K+ channel (TASK)-1 and TASK-2 gene transcripts in murine bladder, and immunohistochemistry and Western blot analysis showed TASK-1 and TASK-2 channel expression and distribution in smooth muscle tissues and cells.TASK channels are expressed in bladder smooth muscle and contribute to the basal K+ conductances responsible for resting membrane potential.