H,K,ATPASE FUNCTION IN POTASSIUM HOMEOSTASIS

本研究的长期目标是研究H，K-ATP酶的作用， 在钾稳态中的作用，并确定这些离子动力 泵由离子通道调节。H、K-ATP酶在肾脏疾病中的作用 钾保存，但现在很明显，肾脏具有 几种不同的H，K-ATPase酶活性，可能反映了 多个基因产物的存在。具体目标1中的实验将 确定H，K-ATP酶亚基同种型的分子身份， 负责特定的酶活性，以及钾和质子 通过对携带靶基因的动物的研究， H，K-ATP酶HK-α-1、HK-α-2或HK-β基因的破坏。 具体目标2中的实验将检查是否敲除HK-α-1， HK-α-2或HK-β亚基影响肾脏或肾脏的正常解剖结构。 钾缺乏的形态学反应。具体目标3 将充分表征新发现的钾渗透离子通道 存在于外膜的内条纹的顶膜上， 髓集合管（OMCD），以及包含这些细胞的细胞类型 渠道这些通道表现出新颖的性质，因为它们似乎是 刺激细胞酸化，而大多数钾离子通道， 因酸中毒而抑制。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），肾脏对钾的破坏的代偿性反应， 这些基因，以及这些基因是否参与了正常的形态， 肾脏或其对钾缺乏的反应。自从积累证据 表明适度的钾缺乏导致或有助于全身性 动脉高血压，并可能导致慢性肾功能不全，这些 研究领域预计将有助于我们了解的作用， 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.