NA+/K+ ATPASE AND CARDIAC FUNCTION

我们的目标是了解Na，K-ATP酶在心脏中的作用， 研究针对几个具体领域。 其中包括1） 鉴定蛋白质对α 1亚基磷酸化的作用 激酶A在调节心脏功能，特别是收缩性中的作用 和心率; 2）确定强心苷受体位点是否 的Na，K-ATP酶的生理功能，和3）鉴定和 描述了一种新的插入突变体的基因， 在我们的实验室里发现了影响心脏功能的基因。 这 突变体不直接涉及Na，K-ATP酶，但起源于我们的 Na，K-ATP酶基因表达的转基因研究。 最近的研究表明，Na，K-ATP酶的α 1亚基是 蛋白激酶A和Na，K-ATP酶的磷酸化， 受激素和配体的调节，这些激素和配体使用蛋白激酶A作为 信号转导通路中的末端调节因子。 这是我们的 目的是确定蛋白激酶A磷酸化Na，K- ATP酶在调节心脏功能中起作用。 利用胚胎干细胞和基因 靶向技术，小鼠磷酸化位点（丝氨酸943）将被 被丙氨酸取代，并控制心脏功能，包括 收缩性和心率将在磷酸化减 动物 虽然已知Na，K-ATP酶是强心苷的受体， 一类用于治疗充血性心力衰竭的药物， 在某些心律失常中，不知道结合位点是否是 生理学上的重要性，即，是 有一个内源性的调节Na，K-ATP酶的作用，在 洋地黄部位 使用ES细胞基因靶向技术，我们的方法是 以产生具有改变的Na，K-ATP酶的小鼠α 2同种型的小鼠 使得其功能完全，但不再对心脏反应， 糖苷 这种亚单位存在于心脏中， 到强心苷。 如果这些动物是正常的， 已知会增加循环抑制剂的血浆水平， 可以得出结论，该部位要么未在体内使用，要么在体内使用， 并没有发挥重要的生理作用。 另一方面， 无论是在发育过程中还是在心脏功能中， Na，K-ATP酶的强心苷结合位点起着生理作用， 必须有一种内源性配体。 这些研究与 通过一个共同的目标，即描述Na，K-ATP酶的生理作用， 心脏功能。 最后，一个插入突变体已经被分离出来，作为我们基因的一部分， 改变心脏功能和相关基因的调控研究 责任人将被认定。

Our goal is to understand the role Na,K-ATPase plays in the heart and our studies are directed toward several specific areas. These include 1) identifying the role of phosphorylation of the alpha1 subunit by protein kinase A in the regulation of cardiac function, in particular contractility and heart rate, 2) determining whether the cardiac glycoside receptor site of the Na,K-ATPase serves a physiological function, and 3) identifying and characterizing the gene responsible for a new insertional mutant that has been identified in our laboratory which affects cardiac function. This mutant does not directly involve Na,K-ATPase but originated out of our transgenic studies of Na,K-ATPase gene expression. It has recently been shown that the alpha1 subunit of the Na,K-ATPase is phosphorylated by protein kinase A and Na,K-ATPase was previously shown to be regulated by hormones and ligands which use protein kinase A as the terminal regulator in their signal transduction pathways. Thus, it is our goal to determine whether the protein kinase A phosphorylation of Na,K- ATPase plays a role in regulating heart function. Using ES cell and gene targeting techniques, the mouse phosphorylation site (serine 943) will be replaced with an alanine and the control of heart function including contractility and heart rate will be studied in the phosphorylation minus animals. While it is known that Na,K-ATPase is the receptor for cardiac glycosides, a class of drugs used in the treatment of congestive heart failure and certain arrhythmias, it is not known whether the binding site is of physiological importance ina the absence of cardiac glycosides, i.e., is there an endogenous regulator of the Na,K-ATPase which acts at the digitalis site. Using ES cell-gene targeting techniques, our approach is to produce mice with an altered mouse alpha2 isoform of the Na,K-ATPase such that it is fully functional but no longer responsive to cardiac glycosides. This subunit is present in the heart and is normally sensitive to cardiac glycosides. If the animals are normal even under conditions known to increase the plasma levels of the circulating inhibitor, it would be concluded that this site is either not used in vivo or if so, it does not play a significant physiological role. On the other hand, an altered phenotype either during development or in heart function demonstrates that the cardiac glycoside binding site of the Na,K-ATPase plays a physiological role and that an endogenous ligand must exist. These studies are linked via a common goal, namely to describe the physiological role of Na,K-ATPase in cardiac function. Finally, an insertional mutant has been isolated as part of our gene regulation studies which alters cardiac function and the associated gene responsible will be identified.