T TYPE CALCIUM CHANNELS AND ALDOSTERONE SECRETION

描述（改编自申请人的摘要）：充血性心脏 在人口老龄化中，失败是一个主要的健康问题。 二次 醛固酮增多症显著地使这种管理复杂化， disorder. 过多的醛固酮产生增加血管内容量 并增强心肌纤维化，从而加速 心脏衰竭 抑制醛固酮增多症的新策略将是 对肾功能不全充血性心力衰竭患者的特殊治疗价值 不足 这项研究项目的总体假设是， 阈值，T型，Ca+通道活性是生理性 调节醛固酮分泌并设定肾上腺的反应 肾小球细胞通过其主要生理调节因子激活， 血管紧张素II T-型Ca+通道活性受以下活性调节： Ca +/钙调素（CaM）依赖性蛋白激酶II。 该激酶的激活 降低T型Ca+通道的电压响应， 通道在较低的电压下打开，因此，更多的Ca+被输送到 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依赖性蛋白激酶 调节离体牛肾上腺肾小球细胞的T型Ca+通道; 并确定这一机制在多大程度上被援引和/或 由肾小球细胞促分泌素（细胞外K和血管紧张素）修饰 II（Ang II））在其控制醛固酮分泌中的作用。 他们将使用一个 技术的组合，包括：膜片电极电压钳， 评估通道活性;单细胞荧光以测量细胞内 Ca+稳态;免疫沉淀和Western免疫学方法 印迹以评估Ca +/CaM依赖性蛋白激酶的活化状态 II（CKII）和细胞刺激期间Ca+通道的β亚基。 具体目的是：1）确定CKII 调节T通道活性; 2）确定Ang的作用机制 II-受体激活，导致T-通道活性的变化;和3） 为了确定CKII调节T通道活性的作用， 醛固酮分泌的生理调节。 拟议的研究 将描述调节T型Ca+的生理机制 渠道活动。 这些研究涉及长期临床目标， 改善充血性心力衰竭的临床管理。

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.