At the cross-point of connexins, calcium, and ATP: blocking hemichannels inhibits vasoconstriction of rat small mesenteric arteries
At the cross-point of connexins, calcium, and ATP: blocking hemichannels inhibits vasoconstriction of rat small mesenteric arteries
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DOI：
10.1093/cvr/cvw215
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发表时间：
2017-02-01
影响因子：
10.8
通讯作者：
Leybaert, Luc
中科院分区：
文献类型：
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作者：
Bol, Melissa;Wang, Nan;Leybaert, Luc
目的连接蛋白形成直接连接细胞的间隙连接（GJ），从而协调血管细胞功能并控制血管直径和血流。GJ由两个半通道组成，每个半通道由连接细胞贡献。半通道也作为非连接通道存在，当打开时，导致离子的进入/损失和ATP的逃逸。在这里，我们研究了半通道和Ca 2 +/嘌呤能信号之间的串扰控制血管收缩。我们假设半通道Ca（2+）进入和ATP释放有助于平滑肌细胞（SMC）的Ca 2+动力学，从而影响血管收缩性。我们应用几种半通道功能的肽调节剂和Ca ~（2+）和ATP信号传导的抑制剂来研究它们对SMC Ca ~（2+）动力学和血管收缩性的影响.方法和结果大鼠肠系膜小动脉（SMAs）的共聚焦Ca ~（2+）成像研究表明去甲肾上腺素诱导的SMC Ca ~（2+）振荡通过用xestospongin-C阻断IP_3受体和干扰半通道功能而被抑制，最值得注意的是通过特异性Cx43半通道阻断肽TAT-L2和通过促进Cx43半通道开放的TATCT 9。半通道参与SMC功能的证据得到以下事实的支持：TAT-CT 9显著增加SMC静息细胞质Ca 2+浓度，表明其促进Ca 2+进入，并且观察到去甲肾上腺素触发的血管ATP释放被TAT-L2阻断。对分离的SMA的肌张力测量显示ATP受体拮抗剂苏拉明对去甲肾上腺素触发的收缩性有显著的抑制作用，但TAT-L2的作用最强，在37 ℃时抑制率为80%。在条件性Cx43敲除动物中，TAT-L2对血管收缩的抑制显著降低，表明该效应是Cx43半通道依赖性的。计算模型表明，这些结果可以解释由一个单一的hemichannels每个SMC.Conclusions开放这些结果表明，Cx43 hemichannels有助于SMC的Ca 2+动力学和收缩性，通过促进Ca 2+进入，ATP释放，和嘌呤能信号。
Aims Connexins form gap-junctions (GJs) that directly connect cells, thereby coordinating vascular cell function and controlling vessel diameter and blood flow. GJs are composed of two hemichannels contributed by each of the connecting cells. Hemichannels also exist as non-junctional channels that, when open, lead to the entry/loss of ions and the escape of ATP. Here we investigated cross-talk between hemichannels and Ca2+/purinergic signalling in controlling blood vessel contraction. We hypothesized that hemichannel Ca(2+)entry and ATP release contributes to smooth muscle cell (SMC) Ca2+ dynamics, thereby influencing vessel contractility. We applied several peptide modulators of hemichannel function and inhibitors of Ca2+ and ATP signalling to investigate their influence on SMC Ca2+ dynamics and vessel contractility.Methods and results Confocal Ca(2+)imaging studies on small mesenteric arteries (SMAs) from rat demonstrated that norepinephrineinduced SMC Ca2+ oscillations were inhibited by blocking IP3 receptors with xestospongin-C and by interfering with hemichannel function, most notably by the specific Cx43 hemichannel blocking peptide TAT-L2 and by TATCT9 that promotes Cx43 hemichannel opening. Evidence for hemichannel involvement in SMC function was supported by the fact that TAT-CT9 significantly increased SMC resting cytoplasmic Ca2+ concentration, indicating it facilitated Ca2+ entry, and by the observation that norepinephrine-triggered vessel ATP release was blocked by TAT-L2. Myograph tension measurements on isolated SMAs showed significant inhibition of norepinephrinetriggered contractility by the ATP receptor antagonist suramin, but the strongest effect was observed with TAT-L2 that gave similar to 80% inhibition at 37 degrees C. TAT-L2 inhibition of vessel contraction was significantly reduced in conditional Cx43 knockout animals, indicating the effect was Cx43 hemichannel-dependent. Computational modelling suggested these results could be explained by the opening of a single hemichannel per SMC.Conclusions These results indicate that Cx43 hemichannels contribute to SMC Ca2+ dynamics and contractility, by facilitating Ca2+ entry, ATP release, and purinergic signalling.