Inhibition of TASK1-like channels by muscarinic receptor stimulation in rat adrenal medullary cells
Inhibition of TASK1-like channels by muscarinic receptor stimulation in rat adrenal medullary cells
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DOI：
10.1111/j.1471-4159.2008.05521.x
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发表时间：
2008-08-01
影响因子：
4.7
通讯作者：
Warashina, Akira
中科院分区：
文献类型：
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作者：
Inoue, Masurni;Harada, Keita;Warashina, Akira
已知毒蕈碱受体参与各种哺乳动物肾上腺髓质（AM）细胞中乙酰胆碱诱导的儿茶酚胺分泌。然而，离子机制尚未阐明。因此，我们研究了急性分离的大鼠AM细胞与穿孔膜片钳方法的问题。浴应用30 μ M毒蕈碱诱导去极化，随后产生动作电位或负膜电位下的内向电流。毒蕈碱敏感电流在施加没有时间依赖性分量的命令脉冲时瞬时改变幅度，改变作为K（+）电极的极性，并显示Goldman-Hodgkin-Katz（GHK）类型的整流。当pH值为7.09时，-20 mV的全细胞电流被半抑制浓度的H（+）离子抑制，而在pH值降至6.5的盐水中，毒蕈碱不能诱导进一步的内向电流。当含毒蕈碱的盐水中的pH值降至6.6时，分泌物中也发生了类似的阻塞。RT-PCR、免疫印迹和免疫细胞化学结果表明，大鼠AM细胞主要表达TASK 1通道。AM细胞中的这个ASK通道可以直接感知运动期间血液pH值的降低。muscarine行动是模仿oxotremorine-methiodide，但不是oxotremorine。目前的结果表明，激活毒蕈碱受体或降低外部pH值在大鼠AM细胞诱导分泌通过抑制TASK 1样通道。
The muscarinic receptor is known to be involved in the acetylcholine-induced secretion of catecholamines in the adrenal medulla (AM) cells of various mammals. The ionic mechanisms, however, have not been elucidated yet. Thus, we investigated the issue in acutely isolated rat AM cells with the perforated patch clamp method. Bath application of 30 mu M muscarine induced depolarization with the consequent generation of action potentials or an inward current at negative membrane potentials. The muscarine-sensitive current instantaneously changed in amplitude upon application of command pulses without a time-dependent component, altered the polarity as a K(+)-electrode, and showed rectification of the Goldman-Hodgkin-Katz (GHK) type. The whole-cell current at -20 mV was inhibited by external H(+) ions with a concentration responsible for half inhibition of pH 7.09 and muscarine failed to induce a further inward current during exposure to a saline in which pH decreased to 6.5. A similar occlusion occurred in secretion when pH in muscarine-containing saline decreased to 6.6. RT-PCR, immunoblotting, and immunocytochemistry suggested that rat AM cells mainly express the TASK1 channel. This TASK channel in AM cells may directly sense a decrease in blood pH, which occurs during exercise. The muscarine action was mimicked by oxotremorine-methiodide, but not by oxotremorine. The present results indicate that activation of muscarinic receptors or a decrease in external pH in the rat AM cell induces secretion through the inhibition of TASK1-like channels.