Department of Neurosurgery, The First Affiliated Hospital of Kunming Medical University, 295 Xichang Road, Kunming, 650032, China.
Yunnan Key Laboratory of Laboratory Medicine, Kunming, 650032, China.
Neurotherapeutics. 2019 Jul;16(3):901-911. doi: 10.1007/s13311-019-00741-4.
Cerebral blood flow (CBF) reduction underlies unfavorable outcomes after subarachnoid hemorrhage (SAH). Transient receptor potential melastatin-4 (TRPM4) has a pivotal role in cerebral artery myogenic tone maintenance and CBF regulation under physiological conditions. However, the role of TRPM4 in CBF reduction after SAH is unclear. In this study, we aimed at testing whether TRPM4 would contribute to CBF reduction after SAH in vivo and determining underlying mechanisms. Rat SAH model was established by stereotaxic injection of autologous nonheparinized arterial blood at the suprasellar cistern. A TRPM4 blocker, 9-phenanthrol (9-Phe), was infused through an intraventricular catheter connected to a programmed subcutaneous pump to evaluate the contribution of TRPM4 to SAH outcomes. TRPM4 expression and translocation in cerebral artery myocytes were detected by immunoblotting. Macroscopic currents in cerebral artery myocytes were determined by whole-cell patch clamp. Myogenic tone of cerebral arteries was studied by pressurized myography. Cortical and global CBFs were measured via laser Doppler flowmetry and fluorescent microspheres, respectively. After SAH, TRPM4 translocation and macroscopic current density increased significantly. Furthermore, TRPM4 accounted for a greater proportion of myogenic tone after SAH, suggesting an upregulation of TRPM4 activity in response to SAH. Cortical and global CBFs were reduced after SAH, but were restored significantly by 9-Phe, implying that TRPM4 contributed to CBF reduction after SAH. Collectively, these discoveries show that increased TRPM4 activity has a pivotal role in CBF reduction after SAH, and provide a novel target for the management of cerebral perfusion dysfunction following SAH.
脑血流（CBF）减少是蛛网膜下腔出血（SAH）后不良结局的基础。瞬时受体电位 melastatin-4（TRPM4）在生理条件下维持脑动脉肌源性张力和调节 CBF 方面起着关键作用。然而，TRPM4 在 SAH 后 CBF 减少中的作用尚不清楚。在这项研究中，我们旨在测试 TRPM4 是否会导致体内 SAH 后 CBF 减少，并确定潜在的机制。通过立体定向向鞍上池注射自体未肝素化动脉血来建立大鼠 SAH 模型。通过与程控皮下泵相连的脑室内导管输注 TRPM4 阻断剂 9-菲（9-Phe），以评估 TRPM4 对 SAH 结果的贡献。通过免疫印迹检测脑动脉肌细胞中 TRPM4 的表达和易位。通过全细胞膜片钳测定脑动脉肌细胞的宏观电流。通过加压血管描记术研究脑动脉的肌源性张力。通过激光多普勒血流仪和荧光微球分别测量皮质和全脑 CBF。SAH 后，TRPM4 易位和宏观电流密度显著增加。此外，TRPM4 在 SAH 后占肌源性张力的比例更大，表明 TRPM4 活性在 SAH 后上调。SAH 后皮质和全脑 CBF 减少，但 9-Phe 可显著恢复，提示 TRPM4 参与 SAH 后 CBF 减少。总之，这些发现表明，TRPM4 活性增加在 SAH 后 CBF 减少中起着关键作用，并为 SAH 后脑灌注功能障碍的管理提供了新的靶点。
