Tonic inhibition of murine proximal colon is due to nitrergic suppression of Ca2+ signaling in interstitial cells of Cajal
Tonic inhibition of murine proximal colon is due to nitrergic suppression of Ca2+ signaling in interstitial cells of Cajal
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DOI：
10.1038/s41598-019-39729-7
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发表时间：
2019-03-13
影响因子：
4.6
通讯作者：
Sanders, Kenton M.
中科院分区：
文献类型：
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作者：
Drumm, Bernard T.;Rembetski, Benjamin E.;Sanders, Kenton M.
结肠平滑肌细胞 (SMC) 的自发兴奋性和收缩通常受到抑制性运动神经元输入的抑制，这种行为称为强直抑制。介导强直抑制的结后细胞尚未阐明。我们研究了介导近端结肠强直性抑制的结后细胞，以及强直性抑制是否是由 Ano1 通道活性抑制引起的，Ano1 通道仅在 Cajal 间质细胞 (ICC) 中表达。我们发现河豚毒素 (TTX)、一氧化氮 (NO) 合成抑制剂 L-NNA 和可溶性鸟苷酸环化酶抑制剂 ODQ 大大增强了结肠收缩。 Ano1 拮抗剂苯溴马隆和 Ani9 抑制 TTX、L-NNA 和 ODQ 的作用。在 ICC 中，Ano1 通道被内质网 (ER) 释放的 Ca2+ 激活，用 SERCA 抑制剂 (thapsigargin) 或钙池操纵的 Ca(2+) 进入阻滞剂 (GSK 7975 A) 阻断 Ca2+ 释放可逆转 TTX、L-NNA 和 ODQ 的作用。 Ca2+ 成像显示，TTX、L-NNA 和 ODQ 增加了结肠 ICC 中的 Ca2+ 瞬时放电。我们的结果表明，近端结肠的强直性抑制是通过抑制 ICC 中的 Ca2+ 释放事件而发生的。 ICC 中 Ca2+ 释放的抑制限制了 Ano1 通道的开放概率，降低了电耦合 SMC 的兴奋性。
Spontaneous excitability and contractions of colonic smooth muscle cells (SMCs) are normally suppressed by inputs from inhibitory motor neurons, a behavior known as tonic inhibition. The post-junctional cell(s) mediating tonic inhibition have not been elucidated. We investigated the post-junctional cells mediating tonic inhibition in the proximal colon and whether tonic inhibition results from suppression of the activity of Ano1 channels, which are expressed exclusively in interstitial cells of Cajal (ICC). We found that tetrodotoxin (TTX), an inhibitor of nitric oxide (NO) synthesis, L-NNA, and an inhibitor of soluble guanylyl cyclase, ODQ, greatly enhanced colonic contractions. Ano1 antagonists, benzbromarone and Ani9 inhibited the effects of TTX, L-NNA and ODQ. Ano1 channels are activated by Ca2+ release from the endoplasmic reticulum (ER) in ICC, and blocking Ca2+ release with a SERCA inhibitor (thapsigargin) or a store-operated Ca(2+ )entry blocker (GSK 7975 A) reversed the effects of TTX, L-NNA and ODQ. Ca2+ imaging revealed that TTX, L-NNA and ODQ increased Ca2+ transient firing in colonic ICC. Our results suggest that tonic inhibition in the proximal colon occurs through suppression of Ca2+ release events in ICC. Suppression of Ca2+ release in ICC limits the open probability of Ano1 channels, reducing the excitability of electrically-coupled SMCs.