MODELS FOR GENETIC DISORDERS OF ACID-BASE TRANSPORT

我们的长期目标是详细了解离子的生理功能， 参与胃肠道中离子分泌和吸收以及肾脏对酸/碱的控制的转运蛋白 和电解质平衡为了实现这一目标，我们正在使用基因靶向技术来检查基因组。 特定转运蛋白的体内功能。我们已经开发了NHE 1、2和3 Na/H的无效突变小鼠 交换蛋白，结肠和胃H，K-ATP酶（cHKA和gHKA），噻嗪敏感性NaCl协同转运蛋白，以及 基底外侧NaK 2Cl协同转运蛋白（NKCC 1）。本提案的目的1是开发NHE 4的无效突变小鼠 Na/H交换器、AE 2和NBC 1/HCO 3交换器、NBC 1 Na/HCO 3共转运体和C1 C-2 Cl 渠道，并进行初步分析，他们的表型。在目标2中， 分析胃HC 1和KC 1分泌和粘膜保护。这些研究将检验以下假设： C1 C-2、AE 2和NHE 4是胃壁细胞分泌HCl所必需的; NHE 2在粘膜中起作用， 保护和维持壁细胞活力在酸分泌;和NKCC 1是需要最大 KC 1由胃腺分泌。在aim 3中，研究了细胞内吸收和分泌的转运机制， 将分析肠道。这些研究将测试以下各项的功能： 介导Cl吸收; AE 2作为基底外侧C1/HCO 3交换器介导HCC>3吸收; NHE 1和 NKCC 1在毒素刺激的分泌中; NHE 2在减轻炎症状态的严重程度中; cHKA在钾循环中。 结肠，并为结肠炎状态提供补偿。在目标4中， 将分析肾功能中的特异性转运蛋白。在这些研究中，我们将：分析小鼠的肾脏表型 缺乏NKCC 1、AE 2和NHE 2;检测cHKA和gHKA在集合管重吸收HCO 3中的功能 和在钾缺乏期间尿钾的保存;并分析NBC 1和 NHE 3在近端小管重吸收HCOa和酸碱平衡中的作用。这些研究将大大 扩展我们对单个转运蛋白的特定功能以及它们如何协同工作进行调解的理解 体内跨上皮离子转运过程。

Our long-term objective is to develop a detailed understanding of the physiological functions of ion transporters involved in secretion and absorption of ions in the gastrointestinal tract and in renal control of acid/base and electrolyte homeostasis. In working toward this goal, we are using gene targeting technology to examine the in vivo functions of specific transporters. We have already developed null mutant mice for the NHE1, 2, and 3 Na/H exchangers, the colonic and gastric H,K-ATPases (cHKA and gHKA), the thiazide-sensitive NaCl cotransporter, and the basolateral NaK2Cl cotransporter (NKCC1). Aim 1 of this proposal is to develop null mutant mice for the NHE4 Na/H exchanger, the AE2 and DRA C1/HCO3 exchangers, the NBC1 Na/HCOs cotransporter, and the C1C-2 Cl channel, and to perform the initial analyses of their phenotypes. In aim 2, the transport mechanisms underlying gastric HC1 and KC1secretion and mucosal protection will be analyzed. These studies will test the hypotheses that C1C-2, AE2, and NHE4 are essential for HC1secretion by the gastric parietal cell; that NHE2 functions in mucosal protection and in maintaining parietal cell viability during acid secretion; and that NKCC1 is required for maximum KC1 secretion by gastric glands. In aim 3, the transport mechanisms underlying absorption and secretion in the intestinal tract will be analyzed. These studies will test the functions of: DRA as the apical Cl/HCOs exchanger mediating Cl absorption; AE2 as the basolateral C1/HCO3 exchanger mediating HCC>3 absorption; NHE1and NKCC1 in toxin-stimulatedsecretion; NHE2 in blunting the severity of diarrheal states; and cHKA in K recycling in the colon and in providing compensation for diarrheal states. In aim 4, the function and relative importance of specific transporters in renal function will be analyzed. In these studies we will: analyze the renal phenotypes of mice lacking NKCC1, AE2, and NHE2; test the functions of cHKA and gHKA in HCO3 reabsorption in the collecting duct and in urinary potassium conservation during potassium depletion; and analyze the relative importance of NBC1 and NHE3 in HCOa reabsorption in the proximal tubule and in acid-base homeostasis. These studies will substantially expand our understanding of the specific functions of individual transporters and how they work together to mediate transepithelial ion transport processes in vivo.