Models of Ion Transport Defects in Heart and Lung

描述(由申请人提供)：我们的长期目标是了解一系列离子转运蛋白的生理功能，这些转运蛋白在体内维持心血管和肺组织中的酸碱、电解质和钙稳态。其中包括至少8个HCO3转运体、NHE1钠/氢交换器、NKCC1 Na-K-2CI共转运体和至少7个钙泵。除了少数例外，特定异构体的活性在体内或体外都无法区分。为了了解每个转运蛋白的生理作用和相对重要性，我们正在系统地开发和分析基因靶向和转基因小鼠模型。我们已经开发了许多这样的模型，并确定了涉及心功能、缺血-再灌注损伤、血压、血管和气道平滑肌张力、呼吸道阴离子分泌等表型。在目标1中，我们将发展Na-HCO3共转运体和钙泵的基因敲除小鼠，以及允许挽救AE1和AE2CI/HCO3交换器和NHE1Na/H交换器敲除的严重表型的转基因小鼠。在目标2中，我们将确定转运蛋白功能障碍在心血管组织和肺中的生理后果。具体地说，我们将分析：a)心功能，以确定零突变是否以及在多大程度上影响心功能，并改变对缺血再灌注损伤和肥大刺激的反应；b)整个动物水平的血压以及组织水平的血管平滑肌收缩和离子动态平衡；c)机械通气小鼠在正常条件下和支气管收缩肌激发后的肺功能；以及d)隔离气道准备中涉及跨跨上皮阴离子电流和平滑肌张力的离子转运机制。这些研究将检验正在研究的酸碱、电解质和钙转运体调节心脏收缩能力以及肺和血管平滑肌张力和收缩能力的假设，这反过来又影响健康和疾病中的心功能、动脉血压和呼吸道阻力。我们预计，这项研究中正在开发的新的小鼠品系将像已经开发的模型一样，成为分析这些离子转运体调节心血管、肺和其他组织的生理功能的机制的有价值的模型。

DESCRIPTION (provided by applicant): Our long-term objective is to develop an understanding of the physiological functions of a broad array of ion transporters that maintain acid-base, electrolyte, and Ca homeostasis in cardiovascular and pulmonary tissues in vivo. These include at least 8 HCO3 transporters, the NHE1 Na/H exchanger, the NKCC1 Na-K-2CI cotransporter, and at least 7 Ca pumps. With few exceptions, the activities of specific isoforms cannot be distinguished in vivo or in vitro. To understand the physiological role and relative importance of each transporter, we are systematically developing and analyzing gene-targeted and transgenic mouse models. We have already developed many of these models, and have identified phenotypes involving cardiac performance, ischemic-reperfusion injury, blood pressure, vascular and airway smooth muscle tone, airway anion secretion, and others. In Aim 1 we will develop knockout mice for both Na-HCO3 cotransporters and Ca pumps and transgenic mice that allow rescue of severe phenotypes for the AE1 and AE2 CI/HCO3 exchangers and NHE1 Na/H exchanger knockouts. In Aim 2 we will determine the physiological consequences of transporter dysfunction in cardiovascular tissues and lung. Specifically, we will analyze: a) cardiac function to determine whether, and to what extent, the null mutations affect cardiac performance and alter responses to ischemic-reperfusion injury and hypertrophic stimuli, b) blood pressure at the whole animal level and vascular smooth muscle contractility and ion homeostasis at the tissue level, c) pulmonary function in mechanically ventilated mice under normal conditions and following bronchoconstrictor challenge, and d) ion transport mechanisms involved in transepithelial anion currents and smooth muscle tone in isolated airway preparations. These studies will test the hypotheses that the acid-base, electrolyte, and Ca transporters being studied regulate cardiac contractility and pulmonary and vascular smooth muscle tone and contractility, which in turn affect cardiac function in health and disease, arterial blood pressure, and airway resistance. We anticipate that the new mouse lines being developed in this proposal will, like the models already developed, become valuable models for analysis of the mechanisms by which these ion transporters regulate the physiological functions of cardiovascular, pulmonary, and other tissues.