Renovascular Calcium Channels in Hypertension

描述(申请人提供)：这是一个为期3年的试点项目的竞争性更新，目的是确定系统性高血压期间肾动脉上调L型钙通道的机制，这是一种关键的适应性反应，可以防止压力导致的肾脏毛细血管床损伤。在资助的头两年，我们记录了高血压与两种高血压大鼠模型的肾血管平滑肌细胞(SMC)中形成孔的钙通道α1c亚单位表达增加之间的正相关关系。重要的是，这种Alpha1c亚单位表达的增加与受影响动脉的SMC中钙通道电流和钙依赖张力的增加有关。在过去的6个月里，我们启动了一种肾脏SMC培养模型的特征，该模型将适合于识别诱导α1c亚基表达的机制，包括SMC膜的膜去极化。RT-PCR和Western印迹分析显示，SMC在第5代中表达α1c和辅助的β1-4亚基，并在KCl诱导的去极化反应中显著上调α1c亚基。基于这些关键的初步数据，我们将追求特定的目标，以确定：(A)肾血管SMC中钙通道的分子组成，(B)介导膜去极化反应中α1c和β亚基上调的细胞通路，(C)辅助β1-4亚基在影响alpa1C亚单位靶向/转运到质膜中的作用，以及(D)CAL的疾病特异性分布。高血压大鼠肾动脉通道的表达和组成。找出上调Cal的机制。暴露在高血压下的血管平滑肌细胞的钙通道将有助于为开发基于离子通道的新策略奠定基础，以减少包括高血压在内的血管痉挛疾病中异常的钙依赖张力。

DESCRIPTION (provided by applicant): This is a competitive renewal of a 3-year pilot project to identify the mechanisms by which renal arteries upregulate L-type Ca 2+ (CaL) channels during systemic hypertension, a critical adaptive response that prevents pressure-induced damage of the renal capillary beds. During the first two years of funding, we have documented a positive relationship between elevated blood pressure and an increased expression of the pore-forming alpha1c subunit of CaL channels in renovascular smooth muscle cells (SMCs) from two rat models of hypertension. Importantly, this increase in alpha1c subunit expression was associated with an increased CaL channel current and Ca2+-dependent tone in the SMCs of the affected arteries. In the last 6 months, we initiated the characterization of a renal SMC culture model that will be suitable for identifying mechanisms that induce the expression of alpha1c subunits, including membrane depolarization of SMC membranes. The SMCs express both alpha1c and ancillary beta1-4subunits through passage 5 as assessed by RT-PCR and Western blot, and profoundly upregulate alpha1c subunits in response to KCl-induced depolarization. Based on these key preliminary data, we will pursue specific aims directed toward identifying: (a) the molecular composition of CaL channels in renovascular SMCs, (b) the cellular pathways that mediate the upregulation of alpha1c and beta subunits in response to membrane depolarization, (c) the role of accessory beta1-4subunits in affecting targeting/trafficking of the alpa1C subunit to the plasma membrane and (d) a disease-specific profile of CaL. channel expression and composition in renal arteries of hypertensive rats. Identifying the mechanisms that upregulate CaL. channels in vascular SMCs exposed to high blood pressure will help set the stage for developing new ion channel-based strategies to reduce abnormal Ca2+-dependent tone in vasospastic diseases including essential hypertension.