H,K,ATPASE FUNCTION IN POTASSIUM HOMEOSTASIS

这项研究的长期目标是研究H，K-ATPase的作用 在钾的动态平衡和确定这些离子动力如何 泵由离子通道调节。H，K-ATPase对肾脏的重要作用 钾守恒，但现在很明显，肾脏拥有 几种不同的H，K-ATPase活性可能反映了 多种基因产物的存在。在特定目标1中的实验将 确定H，K-ATPase亚基亚基异构体的分子同一性 负责特定的酶活性，以及钾和质子 通过对具有靶向基因的动物的研究，离散肾单位节段中的流量 H，K-ATPase HK-Alpha-1、HK-Alpha-2或HK-beta基因的中断。 在特定目标2中的实验将检查HK-α-1基因敲除， HK-α-2或HK-β亚基影响肾脏的正常解剖或 对钾耗竭的形态反应。特定目标实验3 将全面描述新发现的钾离子通道 它们存在于外层内条纹的顶端膜上 髓集合管(OMCD)及其所含的细胞类型 频道。这些通道显示出新的属性，因为它们看起来 由细胞酸化刺激，而大多数钾通道是 被酸中毒抑制的。拟议的实验旨在建立 这些基因中的每一个对重要的适应性反应的贡献 (钾耗竭)，肾脏对受阻的代偿性反应 这些基因，以及这些基因是否参与了血管的正常形态 肾脏或其对钾耗竭的反应。自从收集证据以来 表明适度的钾缺乏会导致或促进全身性 动脉高血压，并可能导致慢性肾功能不全，这些 研究领域有望有助于我们理解 钾缺乏是肾脏和心血管疾病的危险因素。

The long-range goal of this research is to examine the role of H,K-ATPases in potassium homeostasis and to determine how these ion-motive pumps are regulated by ion channels. H,K-ATPases are important for renal potassium conservation, but it is now apparent that the kidney possesses several different H,K-ATPase enzymatic activities which likely reflect the presence of multiple gene products. Experiments in Specific Aim 1 will determine the molecular identities of the H,K-ATPase subunit isoforms that are responsible for specific enzymatic activities, and for potassium and proton flux in discrete nephron segments, by the study of animals with targeted gene disruption of the H,K-ATPase HK-alpha-1, HK-alpha-2, or HK-beta genes. Experiments in Specific Aim 2 will examine whether knockout of HK-alpha-1, HK-alpha-2, or HK-beta subunits affects the normal anatomy of the kidney or the morphological response to potassium depletion. Experiments in Specific Aim 3 will characterize fully the newly discovered potassium-permeable ion channels that are present at the apical membrane of the inner stripe of the outer medullary collecting duct (OMCD), and the cell types that contain these channels. These channels exhibit novel properties since they appear to be stimulated by cellular acidification whereas most potassium channels are inhibited by acidosis. The proposed experiments are intended to establish the contribution of each of these genes to an important adaptive response (potassium depletion), the compensatory renal response to the disruption of these genes, and whether these genes are involved in the normal morphology of the kidney or its response to potassium depletion. Since accruing evidence indicates that modest potassium depletion causes or contributes to systemic arterial hypertension, and may contribute to chronic renal insufficiency, these studies area expected to contribute to our understanding of the role of potassium depletion as a risk factor for both renal and cardiovascular disease.