Aziz Qadeer, Li Yiwen, Anderson Naomi, Ojake Leona, Tsisanova Elena, Tinker Andrew
From the Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, United Kingdom.
From the Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, United Kingdom
J Biol Chem. 2017 Oct 27;292(43):17587-17597. doi: 10.1074/jbc.M117.810325. Epub 2017 Sep 11.
ATP-sensitive potassium (K) channels are widely expressed in the cardiovascular system, where they regulate a range of biological activities by linking cellular metabolism with membrane excitability. K channels in vascular smooth muscle have a well-defined role in regulating vascular tone. K channels are also thought to be expressed in vascular endothelial cells, but their presence and function in this context are less clear. As a result, we aimed to investigate the molecular composition and physiological role of endothelial K channels. We first generated mice with an endothelial specific deletion of the channel subunit Kir6.1 (eKO) using cre-loxP technology. Data from qRT-PCR, patch clamp, coronary perfusion Langendorff heart experiments, and endothelial cell Ca imaging comparing eKO and wild-type mice show that Kir6.1-containing K channels are indeed present in vascular endothelium. An increase in intracellular [Ca], which is central to changes in endothelial function such as mediator release, at least partly contributes to the endothelium-dependent vasorelaxation induced by the K channel opener pinacidil. The absence of Kir6.1 did not elevate basal coronary perfusion pressure in eKO mice. However, vasorelaxation was impaired during hypoxia in the coronary circulation, and this resulted in greater cardiac injury during ischemia-reperfusion. The response to adenosine receptor stimulation was impaired in eKO mice in single cells in patch clamp recordings and in the intact coronary circulation. Our data support the existence of an endothelial K channel that contains Kir6.1, is involved in vascular reactivity in the coronary circulation, and has a protective role in ischemia reperfusion.
ATP敏感性钾（K）通道广泛表达于心血管系统，在该系统中，它们通过将细胞代谢与膜兴奋性相联系来调节一系列生物活性。血管平滑肌中的K通道在调节血管张力方面具有明确的作用。K通道也被认为表达于血管内皮细胞，但它们在这种情况下的存在和功能尚不清楚。因此，我们旨在研究内皮K通道的分子组成和生理作用。我们首先利用cre-loxP技术构建了内皮特异性缺失通道亚基Kir6.1（eKO）的小鼠。来自qRT-PCR、膜片钳、冠状动脉灌注Langendorff心脏实验以及比较eKO小鼠和野生型小鼠的内皮细胞钙成像的数据表明，含Kir6.1的K通道确实存在于血管内皮中。细胞内[Ca]的增加是内皮功能变化（如介质释放）的核心，它至少部分促成了K通道开放剂吡那地尔诱导的内皮依赖性血管舒张。Kir6.1的缺失并未提高eKO小鼠的基础冠状动脉灌注压力。然而，在冠状动脉循环缺氧期间血管舒张受损，这导致缺血再灌注期间心脏损伤加重。在膜片钳记录的单细胞以及完整的冠状动脉循环中，eKO小鼠对腺苷受体刺激的反应受损。我们的数据支持存在一种包含Kir6.1的内皮K通道，它参与冠状动脉循环中的血管反应性，并在缺血再灌注中具有保护作用。
