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REGULATING NA+/K+ ATPASE ISOFORMS DURING CARDIAC GROWTH

在心脏生长过程中调节 NA /K ATP酶异构体

基本信息

批准号：
2028355
负责人：
YUK-CHOW NG
金额：
$ 18.78万
依托单位：
PENNSYLVANIA STATE UNIV HERSHEY MED CTR
依托单位国家：
美国
项目类别：
财政年份：
1989
资助国家：
美国
起止时间：
1989-08-01 至 1998-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/2028355
关键词：
enzyme structure ferrets fluorescence microscopy gene expression growth /development heart cell heart metabolism hormone regulation /control mechanism intracellular transport isozymes laboratory rat membrane transport proteins myocardium newborn animals rubidium sodium sodium potassium exchanging ATPase thyroid hormones

项目摘要

In myocardium, Na+,K+-ATPase maintains the electrochemical gradient of the cardiac cells, hence, directly and indirectly modulates electrical and contractile activity of the heart. Na+,K+-ATPase consists of an alpha- and a beta-subunit to which multiple isoforms exist, although their physiological function remains unclear. The overall hypothesis to be tested is that during cardiac growth expression of cardiac Na+,K+- ATPase isozyme is differentially regulated, and that individual isozymes serve unique function in regulating intracellular Na+ concentration ([Na]i). Ferret myocardium expresses alpha3 and alpha1 isoforms, in contrast to the commonly studied adult rat heart which expresses predominately alpha1 and alpha2 isoforms. Thus, ferrets provide a useful model to study expression and function of alpha3, which is expressed in human heart along with alpha1 and alpha2. Using ferrets and rats as animal models, the following objectives will be studied: 1) Expression of alpha3 isoform is upregulated during early postnatal development. In neonatal ferret heart, thyroid hormone (TH) treatment preferentially upregulates the alpha3 isoform. The hypothesis will be tested that TH is a physiological regulator in expression of the alpha3 isoform during developmental cardiac growth. Underlying transcriptional and/or post- transcriptional mechanisms will be examined. 2) Myocardium consists of functionally heterogenous myocardial cells. Localized distribution of the isoforms may reveal specialized function of the isozymes. Using in situ hybridization and immunocytochemistry, distribution of the Na+,K+-ATPase isoforms during developmental growth of the myocardium in rats and ferrets will be established. 3) Relative contribution of the pump isoforms to overall pump activity will be determined, under conditions when intracellular Na+ load is altered, by studying Na-pump activity by 86Rb+ uptake, and [Na]i by fluorescence microscopy. Na affinity of the isozymes will be examined directly in isolated myocytes by measuring Na- dependent pump activity using 86Rb+ uptake. Functional consequences in altered isoform expression during development will be examined. A complete understanding in regulation, distribution, and function of the Na+,K+-ATPase isozymes during cardiac growth may prove helpful not only in understanding the physiology and pathophysiology of the myocardium, but also in developing better clinical strategies for use of cardiac glycosides, to which Na+,K+-ATPase is the only known receptor.

在心肌中，Na+，K+-ATP酶维持着心肌细胞的电化学梯度，因此，心脏细胞直接或间接地调节电和心脏的收缩活动。Na+，K+-ATP酶由一个 α-和β-亚基，其中存在多种亚型，尽管其生理功能尚不清楚。总体假设是在心脏生长过程中，心脏Na+，K+- ATP酶同工酶的调节是不同的，在调节细胞内Na+浓度方面具有独特的功能（[Na]i）。雪貂心肌表达α 3和α 1亚型，与通常研究的成年大鼠心脏相反，主要是α 1和α 2同种型。因此，雪貂提供了一个有用的模型来研究α 3的表达和功能，α 3表达于人类心脏沿着有α 1和α 2。利用雪貂和老鼠动物模型，将研究以下目标：1）表达在出生后早期发育过程中，α 3亚型的表达上调。在新生雪貂心脏，甲状腺激素（TH）治疗优先上调α 3同种型。假设将被测试，TH是一种生理调节剂，在心脏发育基础转录和/或后将检查转录机制。 2)Myocardial包括功能异质性心肌细胞。局部分布同工酶可以揭示同工酶的特殊功能。使用原位 Na ~+，K ~+-ATP酶的分布在大鼠心肌发育生长过程中的亚型，雪貂将成立。3)泵的相对贡献将在一定条件下测定总泵活性的异构体当细胞内Na+负荷改变时，通过研究Na泵活性， ~（86）Rb ~+摄取和[Na]i。Na亲和力同工酶将通过测量Na- 依赖性泵活性使用86 Rb+摄取。功能性后果将检查发育期间改变的同种型表达。一完全了解调节，分布和功能， Na+，K+-ATP酶同工酶在心脏生长过程中可能证明不仅有益在理解心肌的生理学和病理生理学方面，而且还有助于开发更好的临床策略，糖苷，其中Na+，K+-ATP酶是唯一已知的受体。