Models of Ion Transport Defects in Heart and Lung

描述（由申请人提供）：我们的长期目标是发展对维持体内心血管和肺组织酸碱、电解质和钙稳态的一系列离子转运体的生理功能的理解。这些包括至少8个HCO3转运体，NHE1 Na/H交换器，NKCC1 Na- k - 2ci共转运体和至少7个Ca泵。除了少数例外，特定同种异构体的活性不能在体内或体外区分。为了了解每种转运体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，并且已经确定了涉及心脏性能、缺血-再灌注损伤、血压、血管和气道平滑肌张力、气道阴离子分泌等的表型。在目标1中，我们将开发Na-HCO3共转运体和Ca泵的敲除小鼠和转基因小鼠，这些小鼠可以挽救AE1和AE2 CI/HCO3交换器和NHE1 Na/H交换器敲除的严重表型。在目的2中，我们将确定转运蛋白功能障碍在心血管组织和肺部的生理后果。具体来说，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脏功能并改变对缺血-再灌注损伤和肥厚刺激的反应；b)全动物水平的血压和组织水平的血管平滑肌收缩力和离子稳态；c)正常条件下和支气管收缩刺激后机械通气小鼠的肺功能。d)离体气道制剂中涉及上皮阴离子电流和平滑肌张力的离子转运机制。这些研究将验证所研究的酸碱、电解质和钙转运体调节心脏收缩力、肺和血管平滑肌张力和收缩力的假设，这反过来影响健康和疾病时的心功能、动脉血压和气道阻力。我们预计，在本提案中开发的新小鼠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.