T TYPE CALCIUM CHANNELS AND ALDOSTERONE SECRETION

描述(改编自申请者摘要)：充血性心脏 在老龄化人口中，失败是一个主要的健康问题。次要的 醛固酮增多症使这一疾病的处理大大复杂化。 无序。过量的醛固酮产生增加了血管内容量 并增强心肌纤维化，从而加速心脏功能的下降。 心脏衰竭。抑制醛固酮过多症的新策略是 肾功能不全充血性心力衰竭的特殊治疗价值 不够用。这项研究项目的总体假设是 阈值，T-型，钙通道活性是生理基础 调节醛固酮的分泌和肾上腺的反应 肾小球细胞被其主要的生理调节因子激活， 血管紧张素Ⅱ.T型钙通道活性受血管紧张素转换酶活性的调节 钙/钙调蛋白(CaM)依赖的蛋白激酶11。该激酶的激活 降低T型钙通道的电压响应，实现更多 以较低的电压打开通道，从而将更多的钙离子输送到 用于细胞激活的细胞内部。拟议工作的重点是 双重：确定Ca+/CaM依赖的蛋白激酶的机制 调节分离的牛肾上腺肾小球细胞的T型钙通道； 并确定该机制被调用和/或 被肾小球细胞促分泌剂(细胞外钾和血管紧张素)修饰 II(Ang II)对醛固酮分泌的控制作用。他们将使用一个 组合技术包括：将膜片电极电压钳 评估通道活性；单细胞荧光测量细胞内 钙离子稳态；免疫沉淀法和免疫印迹法 印迹法检测钙/钙调素依赖性蛋白激酶的激活状态 在细胞刺激过程中，CKII和钙通道的β亚基。 具体目标是：1)确定长江基建二期工程的机制 调节T通道活动；2)确定血管紧张素转换酶的作用机制(S II-受体激活，导致T-通道活性改变；以及3) 确定CKII对T通道活性的调节作用 醛固酮分泌的生理调节。建议进行的研究 将描述调节T-型钙离子的生理机制 通道活动。这些研究与长期的临床目标有关 提高充血性心力衰竭的临床管理水平。

DESCRIPTION (Adapted from the Applicant's Abstract): Congestive heart failure is a major health problem in an aging population. Secondary hyperaldosteronism significantly complicates the management of this disorder. Excessive aldosterone production increases intravascular volume and enhances myocardial fibrosis, and thus accelerates the decline of the failing heart. Novel strategies to suppress hyperaldosteronism would be of special therapeutic value to congestive heart failure patients with renal insufficiency. The overall hypothesis of this research project is that low threshold, T-type, Ca+ channel activity underlies the physiological regulation of aldosterone secretion and sets the response of the adrenal glomerulosa cell to activation by its major physiological regulator, angiotensin II. T-type Ca+ channel activity is modulated by the activity of Ca+/calmodulin (CaM) dependent protein kinase ll. Activation of this kinase lowers the voltage-response of the T-type Ca+ channel, enabling more channels to open at a lower voltage, and thus, more Ca+ to be delivered into the cell interior for cell activation. The focus of the proposed work is two-fold: to define the mechanism by which Ca+/CaM-dependent protein kinase regulates T-type Ca+ channels in isolated bovine adrenal glomerulosa cells; and to determine the extent to which this mechanism is invoked by and/or modified by glomerulosa cell secretagogues (extracellular K and angiotensin II (Ang II)) in their control of aldosterone secretion. They will use a combination of techniques including: the patch-electrode voltage-clamp to assess channel activity; single cell fluorescence to measure intracellular Ca+ homeostasis; immunological methods of immunoprecipitation and Western blotting to assess the activation state of Ca+/CaM-dependent protein kinase II (CKII) and the beta subunit of the Ca+ channel during cell stimulation. The Specific Aims are: 1) to determine the mechanism by which CKII regulates T-channel activity; 2) to determine the mechanism(s) of Ang II-receptor activation that result in changes in T-channel activity; and 3) to determine the role of CKII regulation of T-channel activity in the physiological regulation of aldosterone secretion. The proposed studies will delineate physiological mechanisms that operate to regulate T-type Ca+ channel activity. These studies relate to the long-term clinical goal of improving the clinical management of congestive heart failure.