REGULATION OF NA/K PUMP CURRENT IN THE HEART

心脏 NA/K 泵电流的调节

• 批准号: 6537165
• 负责人: Richard T Mathias
• 金额: $ 33.86万
• 依托单位: STATE UNIVERSITY NEW YORK STONY BROOK
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-05-01 至 2005-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6537165
• 关键词: autonomic nervous system; biological signal transduction; calcium flux; cardiac myocytes; enzyme mechanism; guinea pigs; heart electrical activity; heart innervation; isozymes; laboratory rabbit; membrane potentials; neuroregulation; phosphorylation; protein kinase C; protein structure function; sodium potassium exchanging ATPase; tissue /cell culture; voltage /patch clamp

DESCRIPTION (adapted from applicant's description): The Na/K pumps establish the cell's transmembrane gradients in Na and K. These are essential for excitability, and the energy stored in the Na-gradient is used by Na/Ca exchange to maintain Ca homeostasis. Moreover, the pump generates an outward current that directly affects the cardiac action potential. Changes in Na/K pump activity can lead directly to arrhythmias, or through effects on Na/Ca exchange, lead to Ca overload and sudden death. Previous studies by the applicant have shown that guinea pig ventricular myocytes co-express the alpha1-and alpha2-isoforms, which have isoform specific, Ca-dependent coupling to autonomic input. The general questions addressed in this proposal are: What is the physiological purpose of this elaborate regulatory scheme, and how are the different signal transduction cascades coupled to each isoform? Preliminary data suggest the following hypotheses: Beta-adrenergic effects on the amount of Na/K pump current are through cycling of vesicles containing the alpha1-isoform; effects on voltage dependence are through direct phosphorylation and Ca-binding. The alpha1-isoform is regulated primarily for Ca homeostasis: the alpha2-isoform is regulated primarily to shape electrical activity. Aims 1, 2 & 3 are to investigate the coupling of signal transduction cascades to specific isoforms. Autonomic induced changes in membrane capacitance will be correlated with changes in pump current, while interfering with vesicle trafficking. The phospho-state of the isoforms will be determined using P-32 labeling and phospho-specific antibodies. Aims 4, 5 & 6 are to investigate the role of autonomic regulation of pump current in Ca homeostasis. The whole cell patch clamp technique will be used to characterize the Na/Ca exchanger and the Ca-dependence of the Na/K pump. Computer simulations will help to understand the interactions of these two transport systems with intracellular Ca. Aims 7 & 8 are to investigate how autonomic regulation of pump current directly affects electrical activity. The whole cell patch clamp will be used to inject current into ventricular action potentials, thus, mimicking the direct effects of autonomic mediated changes in pump current. It will also be used to characterize regulation of pump current in SA node pacemaker cells and determine if regulation of pump current (particularly the alpha2 isoform) affects pacemaking.

描述（根据申请人的描述改编）：NA/K泵建立 细胞在Na和K中的跨膜梯度。这些对于 兴奋性，Na/ca使用了存储在Na级别中的能量 维持CA稳态的交换。 此外，泵向外产生 直接影响心脏动作电位的电流。 Na/K的变化 泵活动可以直接导致心律不齐，或通过对Na/Ca的影响 交换，导致CA超负荷和突然死亡。 先前的研究 申请人表明豚鼠心室心肌细胞共表达 alpha1和α2-异型，它们具有同生的特异性，CA依赖性耦合 自主输入。 本提案中解决的一般问题是：什么 是这种精心制作的监管方案的生理目的，以及如何 不同的信号转导级联反复与每个同工型耦合？ 初步数据提出以下假设：β-肾上腺素能对 Na/k泵电流的量是通过循环的囊泡 alpha1-异型;对电压依赖性的影响是直接的 磷酸化和CA结合。 alpha1- iSOOFORM主要调节 CA稳态：Alpha2-ISOOFORM主要调节以塑造电气 活动。 目标1、2和3是研究信号转导的耦合 级联对特定的同工型。 自主神经诱导的膜变化 电容将与泵电流的变化相关，同时干扰 囊泡贩运。 同工型的磷酸化状态将确定 使用P-32标记和磷酸特异性抗体。目标4、5和6是 调查泵电流自主调节在CA稳态中的作用。 整个细胞贴片夹技术将用于表征NA/CA Na/K泵的交换器和CA依赖性。 计算机模拟会 帮助了解这两个运输系统与 细胞内大约 目标7和8是如何调查如何自主法规 泵电流直接影响电活动。 整个细胞斑块夹 将使用将电流注入心室动作电位，因此 模仿泵电流自主介导的变化的直接影响。 它 还将用于表征SA节点中泵电流的调节 起搏器细胞并确定泵电流的调节（尤其是 α2同工型会影响起搏器。