CONTROL OF ANF PRODUCTION IN HYPERTENSION

哺乳动物的心房含有一组具有生物活性的 心房钠尿因子（ANF）。 心房注射 提取物或纯ANF对动物的快速发作 尿钠排泄、利尿和降低血压。 的 哺乳动物ANF基因包含三个外显子， 内含子 主要转录物是前体ANF mRNA（前 ANF mRNA）并被加工成ANF mRNA， 编码152个氨基酸的前体（pre-pro-ANF），其含有24个氨基酸， 氨基酸信号序列。 前原ANF被迅速切割 以产生前ANF，其被加工成ANF并释放到 流通 本文所述的实验将试图 确定可能对调节 ANF基因的转录，转录后加工， 用该方法合成前心钠素和从心房分泌心钠素 体外心脏灌注技术。 前心钠素mRNA表达率 合成将基于将（3 H）尿苷掺入 前心钠素mRNA在标记线性上升期间， 和UTP的比活性，并且，当稳定状态是 （3）前心钠素mRNA的UMP。 处理率 ANF mRNA将基于掺入细胞中的放射性。 心钠素前体细胞中心钠素mRNA和（~ 3 H）UMP比活性的变化 mRNA。 前心钠素mRNA合成的相对速率也将 通过分离的细胞的体外转录来估计 原子核。 前心钠素合成的速率将基于 将（3 H）-苯丙氨酸（phe）掺入pro-ANF中， （3 H）-phe-tRNA的比活性， 前心钠素的标记呈线性上升， （3 H）-phe-tRNA比活性与 pro-ANF中的（3 H）-phe。 分泌速率将由 灌注液中ANF的出现。 胰岛素的作用， 氨基酸利用率，左心房充盈压，乙酰胆碱， 加压素、去甲肾上腺素和地塞米松对 转录，合成前心钠素和分泌的心钠素将是 考察 最后，心房ANF mRNA的总含量， 血浆ANF水平以及前ANF合成率 mRNA和前心钠素和分泌的心钠素将被测量， 盐负荷大鼠心房与容积依赖性高血压 大鼠 这些定量方法将有助于了解更多 心房和血浆ANF水平是如何 在正常和高血压条件下控制。

Mammalian cardiac atria contain a group of biologically active peptides called atrial natriuretic factor (ANF). Injection of atrial extract or pure ANF to animals causes a rapid onset of natriuresis, diuresis and lowering of blood pressure. The mammalian ANF gene contains three exons separated by two introns. The primary transcript is precursor ANF mRNA (pre- ANF mRNA) and is processed to ANF mRNA, which in turn encodes a 152 amino acid precursor (pre-pro-ANF) containing a 24 amino acid signal sequence. The pre-pro ANF is rapidly cleaved to produce pro-ANF which is processed to ANF and released into circulation. The experiments described herein will attempt to identify the factors that may be important in regulating the transcription of ANF gene, post-transcriptional processing, synthesis of pro-ANF and secretion of ANF from atria using the in vitro heart perfusion, techniques. Rates of pre-ANF mRNA synthesis will be based on the incorporation of (3H) uridine into pre-ANF mRNA during the period when labeling is rising linearly, and the specific activity of UTP, and, when a steady state is reached, (3H) UMP in pre-ANF mRNA. Rates of processing of ANF mRNA will be based on the radioactivity incorporated into ANF mRNA and the specific activity of (3H) UMP in pre-ANF mRNA. The relative rates of pre-ANF mRNA synthesis will also be estimated by the in vitro run-off transcription of the isolated nuclei. Rates of pro-ANF synthesis will be based on the incorporation of (3H)-phenylalanine(phe) into pro-ANF, the specific activity of (3H)-phe-tRNA during the period when labeling of pro-ANF is rising linearly and the steady-state relationship between specific activities of (3H)-phe-tRNA and (3H)-phe in pro-ANF. Rates of secretion will be estimated by the appearance of ANF in the perfusate. The effects of insulin, amino acid availability, left-atrial filling pressure, acetylcholine, vasopressin, norepinephrine and dexamethasone on the transcription, synthesis of pro-ANF and secretion of ANF will be examined. Finally, total contents of atrial ANF mRNA, and plasma level of ANF, as well as rates of synthesis of pre-ANF mRNA and pro-ANF and secretion of ANF will be measured in atria from salt-loading rats and volume-dependent hypertensive rats. These quantitative methods will help to understand more completely how the atrial and plasma levels of ANF are controlled under normal and hypertensive conditions.