REGULATION OF NITRIC OXIDE SYNTASE IN CARDIAC MYOCYTES

心钠素（ANF）和脑钠肽（BNP）具有 血管降压作用，而在肾脏中，它们具有强效的利钠利尿作用， 利尿活性。 虽然ANF和BNP具有相似的生物学特性， 活动，有不同的功能与每种激素。 差异包括组织分布、对降解的敏感性， 内肽酶，循环血浆半衰期，生物和 清除受体，储存在分泌颗粒中的肽的形式，和 可能参与基因表达的DNA调控序列。 成人 心钠素基因优先在心房表达， 心室的表达量不到整个心脏的5%。 在 相比之下，心室BNP mRNA占整个心脏的70%以上 程度. 心钠素和脑钠素mRNA水平在心室中增加， 许多不同的病理生理条件的体积和 压力超负荷，包括高血压和心力衰竭。 鉴于 BNP基因主要在心室表达， BNP与ANF在心房和心室中的差异，我们假设 心钠素和脑钠素的合成调控存在明显差异。 的 该提案的目的是定义转录和后 转录机制参与的差异调节， 编码ANF和BNP的基因在病理生理条件下导致 心脏肥大 为此，我们将采用一种新的模式， 心肌肥大，利用培养的成年猫心肌细胞刺激 用异丙肾上腺素打 具体而言，待检验的假设为： 1)ANF的转录率存在差异， BNP基因，并且进一步地，存在顺式作用调节元件， BNP基因的5'侧翼序列（FS），其不同于 新生儿心肌细胞中ANF基因的特征; 2） 在心脏肥大期间，ANF和BNP基因的再表达涉及 顺式作用调节区不同于参与正常 基因的组织特异性表达; 3）存在不同的反式- 影响ANF和BNP基因表达的作用调节蛋白 静止与跳动的成年猫心肌细胞（肥大的模型 生长）;以及4）ANF和 正常和肥厚心室中的BNP mRNA。 这些研究将 详细分析ANF监管方面的差异， BNP基因，并为理解每个基因的相关性提供基础。 激素在疾病状态中，如高血压和肥大。

Atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP) have vasodepressor effects, while in the kidney they have potent natriuretic and diuretic activities. Although ANF and BNP have similar biological activities, there are distinct features associated with each hormone. Differences include tissue distribution, susceptibility to degradation by endopeptidase, circulating plasma half-life, affinity for biological and clearance receptors, form of the peptide stored in secretory granules, and possible DNA regulatory sequences involved in gene expression. In adult hearts, the gene for ANF is preferentially expressed in the atria, and ventricular expression is less than 5% of that of the whole heart. In contrast, ventricular BNP mRNA represents greater than 70% of whole heart levels. ANF and BNP mRNA levels are augmented in the ventricle subsequent to a number of different pathophysiological conditions of volume and pressure overload, including hypertension and heart failure. Given that the BNP gene is expressed primarily in the ventricles and that the ratio of BNP to ANF is different in atria and ventricles, we hypothesize that there are clear differences in the regulation of synthesis of ANF and BNP. The objective of this proposal is to define transcriptional and post- transcriptional mechanisms involved in the differential regulation of the genes encoding ANF and BNP in pathophysiological conditions resulting in cardiac hypertrophy. To do this, we will make use of a new model of cardiac hypertrophy, utilizing cultured adult feline cardiocytes stimulated to beat with isoproterenol. Specifically, the hypotheses to be tested are: 1) that there are differences in the rates of transcription of the ANF and BNP genes, and furthermore that there are cis-acting regulatory elements in the 5' flanking sequences (FS) of the BNP gene which are distinct from those characterized for the ANF gene in neonatal cardiocytes; 2) that during cardiac hypertrophy reexpression of the ANF and BNP genes involves cis-acting regulatory regions distinct from those involved in normal tissue-specific expression of the genes; 3) that there are different trans- acting regulatory proteins affecting ANF and BNP gene expression in quiescent vs beating adult feline cardiocytes (a model of hypertrophic growth); and 4) that there are differences in the stabilities of ANF and BNP mRNAs in normal and hypertrophied ventricles. Thus, these studies will provide a detailed analysis of the differences in regulation of the ANF and BNP genes, and provide a basis for understanding the relevance of each hormone in disease states, such as hypertension and hypertrophy.