Characterization of the renin-angiotensin system in the turtle Pseudemys scripta.
Characterization of the renin-angiotensin system in the turtle Pseudemys scripta.
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龟 Pseudemys scripta 中肾素-血管紧张素系统的表征。
DOI：
10.1152/ajpregu.1984.247.1.r15
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发表时间：
1984
期刊：
影响因子：
--
通讯作者：
Zehr,JE
中科院分区：
文献类型：
--
作者：
Cipolle,MD;Zehr,JE
在淡水龟Pseudemys scripta中进行了研究，以确定这种爬行动物的肾素-血管紧张素系统的一些特征。透析酸处理的肾脏提取物（1克组织每毫升水）产生了长期的升压反应，在未麻醉的海龟，这是消除煮沸提取物或预处理的海龟与[Sar 1，Ile 8]血管紧张素II。由于在我们的放射免疫分析中使用的抗-[Asp 1，Ile 5，His 9]ANG I与海龟血管紧张素（ANG）的结合较差，因此采用大鼠升压试验。肾脏提取物与同源血浆（pH 5.5和25 ℃）孵育在大鼠中产生时间依赖性升压反应。通过透析或用[Sar 1，Ile 8]ANG II预处理大鼠来消除产物的升压活性。麻醉海龟血管紧张素I的升压反应显着减少，而血管紧张素II的反应保持不变，从而证明在这些动物的血管紧张素转换酶活性的存在。我们测定了在不同稀释度的酶（肾提取物）或底物（血浆）下海龟ANG形成的速度。龟肾提取物与同源血浆孵育显示出典型的米氏动力学。最后，我们进行了实验，以确定是否有一部分海龟血浆肾素以非活性形式存在。胰蛋白酶化引起血浆肾素活性（PRA）略有增加，而酸化至pH 3.3产生了四倍的PRA增加。
Studies were conducted in freshwater turtles Pseudemys scripta to define some characteristics of the renin-angiotensin system in this reptile. Dialyzed acid-treated kidney extract (1 g tissue per ml water) produced a prolonged pressor response in unanesthetized turtles, which was eliminated by boiling the extract or by pretreating the turtle with [Sar1, Ile8]angiotensin II. A rat pressor assay was employed because turtle angiotensin (ANG) was bound poorly by the anti-[Asp1, Ile5, His9]ANG I used in our radioimmunoassay. Kidney extract incubated with homologous plasma (pH 5.5 and 25 degrees C) produced a time-dependent pressor response in rats. The pressor activity of the product was eliminated by dialysis or by pretreating the rats with [Sar1, Ile8]ANG II. The pressor response in anesthetized turtles to ANG I was significantly reduced by captopril, whereas the ANG II response remained unchanged, thus demonstrating the presence of ANG-converting enzyme activity in these animals. We determined the velocity of turtle ANG formation at various dilutions of enzyme (kidney extract) or substrate (plasma). Turtle kidney extract incubated with homologous plasma displayed typical Michaelis-Menten kinetics. Finally we conducted experiments to determine whether a portion of turtle plasma renin exists in an inactive form. Trypsinization caused a slight increase in plasma renin activity (PRA), whereas acidification to pH 3.3 yielded a fourfold increase in PRA.