Vascular Calcium Channel Expression in Hypertension

描述（由申请人提供）：L型Ca2+（CaL）通道是多蛋白复合物，包括成孔11C亚基和较小的辅助亚基。辅助2亚基促进11C亚基在表面膜上的表达，以增加功能性CaL通道的数量。在血管平滑肌细胞（VSMC）中，CaL通道仅稀疏表达以紧密调节电压门控Ca2+内流和血管收缩。然而，在高血压的发展过程中，我们已经表明，CaL通道深刻上调VSMCs燃料异常血管收缩。这个修订项目的目标是确定CaL通道上调对血压升高的反应机制。我们已经注意到，一个特定的2亚基，23，选择性和深刻的增加，在肠系膜循环血管紧张素（Ang II）高血压小鼠。由此产生的CaL通道11C23复合物过多导致受影响动物的小动脉中Ca2+内流升高和异常Ca2+依赖性张力。事实上，药理学阻断CaL通道可显著降低体内Ang II高血压小鼠的血压，但在对照小鼠中几乎没有降压作用，表明CaL通道对高血压的发病机制有重要贡献。在审稿人的要求下，本修订申请紧紧围绕高血压小鼠血管CaL通道异常的机制，以利用基因缺失模型。目的1将确定CaL通道11C23复合物数量的增加是否与两种高血压小鼠模型的VSMCs中的异常Ca 2+内流相关。目的2将使用23敲除小鼠来确定23亚基是否是CaL通道上调和高血压发展的必要贡献者。我们预测，血管CaL通道11C23复合物将无法上调响应血管紧张素II或去甲肾上腺素输注23敲除小鼠，高血压的发展将严重钝化。最后，目标3将利用一种新的微血管检测，我们已经开发出监测钙通道表达的VSMCs的单一，加压小鼠肠系膜动脉。使用这种独特的检测，我们将直接测试的假设，即高腔内压力抑制钙通道的营业额，从而增加其在高血压期间的VSMC表面膜的表达。公共卫生相关性：六千万美国人患有高血压，导致心脏病发作，肾脏疾病和中风。该研究项目将确定血管肌肉细胞中的特定分子是否需要导致动脉收缩过度的膜蛋白异常出现，从而将血压升高到危险水平。

DESCRIPTION (provided by applicant): The L-type Ca2+ (CaL) channels are multi-protein complexes that include a pore- forming 11C subunit and smaller ancillary subunits. The ancillary 2 subunits promote the expression of 11C subunits at the surface membrane to increase the number of functional CaL channels. In vascular smooth muscle cells (VSMCs), CaL channels are only sparsely expressed in order to tightly regulate voltage-gated Ca2+ influx and vascular contraction. However, during the development of hypertension, we have shown that CaL channels profoundly upregulate in the VSMCs to fuel abnormal vasoconstriction. The goal of this revised project is to determine the mechanism of CaL channel upregulation in response to rises in blood pressure. We have noted that a specific 2 subunit, 23, selectively and profoundly increases in the mesenteric circulation of angiotensin (Ang II) hypertensive mice. The resulting overabundance of CaL channel 11C23 complexes results in elevated Ca2+ influx and abnormal Ca2+-dependent tone in the small arteries of the affected animals. In fact, pharmacological block of CaL channels sharply reduces blood pressure in Ang II hypertensive mice in vivo, but has little antihypertensive effect in control mice, suggesting a central contribution of CaL channels to the pathogenesis of hypertension. At the reviewers' behest, this revised application is tightly focused on delineated the mechanism of vascular CaL channel abnormalities in hypertensive mice to take advantage of gene deletion models. Aim 1 will determine if an increased number of CaL channel 11C23 complexes is associated with anomalous Ca2+ influx in VSMCs of two mouse models of hypertension. Aim 2 will use 23 knockout mice to determine if the 23 subunit is a requisite contributor to CaL channel upregulation and the development of hypertension. We predict that vascular CaL channel 11C23 complexes will fail to upregulate in response to Ang II or norepinephrine infusion in 23 knockout mice, and that the development of hypertension will be severely blunted. Finally, Aim 3 will utilize a novel microvascular assay that we have developed to monitor CaL channel expression in the VSMCs of single, pressurized mouse mesenteric arteries. Using this unique assay, we will directly test the hypothesis that high intraluminal pressure inhibits the turnover of CaL channels, thereby increasing their expression at the VSMC surface membrane during hypertension. PUBLIC HEALTH RELEVANCE: Sixty million Americans have high blood pressure, which leads to heart attacks, kidney disease and stroke. This research project will determine if a specific molecule in the muscle cells of blood vessels is required for the abnormal appearance of membrane proteins that causes arteries to contract too much, thereby elevating blood pressure to dangerous levels.