H,K ATPase Function in Potassium Homeostasis

H,K ATP 酶在钾稳态中的功能

• 批准号: 6986946
• 负责人: Charles S Wingo
• 金额: $ 23.44万
• 依托单位: UNIVERSITY OF FLORIDA
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-08-01 至 2009-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6986946
• 关键词: dietary potassium; electrolyte balance; enzyme activity; gastric acid; hydrogen potassium exchanging ATPase; immunocytochemistry; laboratory mouse; light microscopy; messenger RNA; mineralocorticoids; nutrition related tag; potassium channel; protein isoforms; protein localization; renal tubular transport

DESCRIPTION (provided by applicant): The long-range goal of this research is to determine how ion channels coordinate the regulation of H, K-ATPase activity. We established that barium-sensitive pathways (i.e., ion channels) are required for this H, K-ATPase activity in the renal collecting duct (CD). We also found that fundamental differences exist between the mechanism of activation of H, K-ATPase under K-replete conditions when compared to K- restricted conditions. These observations suggest that ion channels play a fundamental role in the operation of H, K-ATPase activity. Disruption of the KCNQ1 gene or pharmacological blockade of this K channel inhibits gastric acid secretion, which occurs via gastric H, K-ATPase. Our preliminary data demonstrate KCNQ1 expression in the mouse renal CD and its regulation by dietary K content and mineralocorticoids. Thus, we hypothesize that these K channels are essential for the operation of H, K-ATPase activity in the CD and are regulated by dietary K and mineralocorticoids. Accordingly, we propose the following Specific Aims: 1. To define the cellular distribution of KCNQ1 and the response of this K channel to changes in mineralocorticoids and dietary K content normal, HKalpha1 null and HKalpha2 null, and HKbeta null mice. 2. To determine the effect of mineralocorticoids and dietary K intake on steady-state mRNA and protein expression of KCNQ1 and KCNE1-5 in the kidney of normal, HKalpha1 null and HKalpha2 null, and HKbeta null mice. 3. To determine whether disruption of the KCNQ1 gene or highly selective inhibitors of KCNQ1 channel activity alter proton secretion in the CD and the mechanism for H, K-ATPase regulation by KCNQ1. 4. To define the pH dependence of KCNQ1 channels that are expressed in the CD and the gastric parietal cell. With the completion of these studies we will know the molecular identities of the KCNQ1 and KCNE1-5 isoforms that are expressed in the CD, if K intake regulates these isoforms, and the role these molecules play in luminal acidification in the CD. Even modest potassium depletion has been shown to cause renal injury and hypertension. These studies will significantly clarify our understanding of renal K homeostasis and potentially how K depletion exacerbates both renal and cardiovascular disease.

描述（由申请人提供）：本研究的长期目标是确定离子通道如何协调 H、K-ATP 酶活性的调节。我们确定肾集合管 (CD) 中的 H,K-ATP 酶活性需要钡敏感途径（即离子通道）。我们还发现，与 K 限制条件相比，K 充足条件下 H,K-ATP 酶的激活机制存在根本差异。这些观察结果表明离子通道在 H,K-ATP 酶活性的运行中发挥着重要作用。 KCNQ1 基因的破坏或该 K 通道的药理阻断会抑制胃酸分泌，胃酸分泌是通过胃 H,K-ATP 酶发生的。我们的初步数据表明 KCNQ1 在小鼠肾 CD 中的表达及其受膳食 K 含量和盐皮质激素的调节。因此，我们假设这些 K 通道对于 CD 中 H，K-ATP 酶活性的运行至关重要，并受到饮食 K 和盐皮质激素的调节。因此，我们提出以下具体目标： 1. 确定 KCNQ1 的细胞分布以及该 K 通道对盐皮质激素和饮食 K 含量正常、HKalpha1 缺失和 HKalpha2 缺失以及 HKbeta 缺失小鼠的变化的反应。 2. 确定盐皮质激素和膳食钾摄入量对正常小鼠、HKalpha1 null 和 HKalpha2 null 以及 HKbeta null 小鼠肾脏中 KCNQ1 和 KCNE1-5 稳态 mRNA 和蛋白表达的影响。 3. 确定 KCNQ1 基因的破坏或 KCNQ1 通道活性的高选择性抑制剂是否会改变 CD 中的质子分泌以及 KCNQ1 调节 H，K-ATP 酶的机制。 4. 定义 CD 和胃壁细胞中表达的 KCNQ1 通道的 pH 依赖性。随着这些研究的完成，我们将了解 CD 中表达的 KCNQ1 和 KCNE1-5 同工型的分子特性、钾摄入量是否调节这些同工型，以及这些分子在 CD 中管腔酸化中所起的作用。即使是适度的钾消耗也已被证明会导致肾损伤和高血压。这些研究将显着阐明我们对肾脏钾稳态以及钾耗竭如何加剧肾脏和心血管疾病的理解。