Dysregulation of blood-brain barrier (BBB) transport exacerbates brain damage in acute ischemic stroke. Here, we aimed to investigate the mechanism of this BBB transport dysregulation by studying the localization and function of pannexin (Px) and connexin (Cx) hemichannels in blood-brain barrier endothelial cells of rat (TR-BBB13 cells) and human (hCMEC/D3 cells) under acute ischemic stroke-mimicking oxygen/glucose deprivation (OGD) and extracellular Ca2+ ([Ca2+]e)-free conditions. TR-BBB13 cells showed increased uptake of hemichannel-permeable sulforhodamine 101, and this increase was markedly inhibited by carbenoxolone, a hemichannel inhibitor. Transcripts of Px1 and Cx43 were detected in TR-BBB13 cells and freshly isolated brain microvascular endothelial cells. The basal compartment-to-cell uptake of hemichannel-permeable propidium iodide was selectively enhanced in hCMEC/D3 cells under [Ca2+]e-free conditions in the basal Transwell chamber. Immunohistochemical analysis revealed the predominant localization of Cx43 on the lateral membranes of hCMEC/D3 cells. [3H]Taurine uptake by hCMEC/D3 cells was significantly reduced in the absence of [Ca2+]e. Functional knock-down of Px1 and Cx43 with mimetic peptides significantly inhibited the increase of ATP release from hCMEC/D3 cells under [Ca2+]e-free conditions. These results suggest that polarized Px1/Cx43 hemichannel opening in brain capillary endothelial cells under acute ischemic stroke-mimicking conditions contributes to dysregulation of BBB transport function, resulting in release of intracellular taurine and ATP.

中文翻译：

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Pannexin 1 / connexin 43的极化半通道开放有助于血脑屏障内皮细胞转运功能的失调。

在急性缺血性中风中，血脑屏障（BBB）转运失调加重了脑损伤。在这里，我们旨在通过研究大鼠（TR-BBB13细胞）和人（hCMEC / D3细胞）在模拟急性缺血性中风的氧/葡萄糖剥夺（OGD）和无细胞外Ca2 +（[Ca2 +] e）的条件下。TR-BBB13细胞显示出对半通道可渗透的磺基若丹明101的摄取增加，并且这种增加被半通道抑制剂羧苄索隆显着抑制。在TR-BBB13细胞和新鲜分离的脑微血管内皮细胞中检测到Px1和Cx43的转录本。在hCMEC / D3细胞中，在无[Ca2 +] e的条件下，在基底Transwell腔室中，选择性地增强了半通道可渗透的碘化丙啶的基底隔室对细胞的吸收。免疫组织化学分析显示，Cx43主要定位在hCMEC / D3细胞的侧膜上。在不存在[Ca2 +] e的情况下，hCMEC / D3细胞对[3H]牛磺酸的摄取显着降低。在无[Ca2 +] e的条件下，模拟肽对Px1和Cx43的功能性敲低显着抑制了hCMEC / D3细胞ATP释放的增加。这些结果表明，在急性缺血性中风模拟条件下，脑毛细血管内皮细胞中极化的Px1 / Cx43半通道开放导致BBB转运功能失调，导致细胞内牛磺酸和ATP的释放。