Hagemann A, Nielsen A H, Poulsen K
Department of Anatomy and Physiology, Royal Veterinary and Agricultural University, Frederiksberg, Denmark.
J Hypertens. 1992 Sep;10(9):959-62.
The aim was to demonstrate whether prorenin is present in plasma from 24-h nephrectomized rats. Its existence and concentration is currently under debate.
Determination of the 50% inhibition concentration (IC50) values for inhibition of plasma renin in intact and 24-h nephrectomized rats. The potent and specific rat renin inhibitor CH-732 was used.
Our previously published method for the determination of rat prorenin was used. It is characterized by removal of an interfering trypsin-formed angiotensin I immunoreactive material before the renin incubation step.
The trypsin-activated prorenin-like activity of 24-h nephrectomized plasma was due only to a minor degree to real prorenin as judged by CH-732 inhibition. The major part of the prorenin-like activity was due to a hitherto unknown sulphydryl enzyme, which could be blocked by N-ethylmaleimide. In normal plasma all prorenin was real prorenin. The plasma concentration of real prorenin in 24-h nephrectomized rats was approximately 10% of that in intact rats.
Prorenin is definitely present in nephrectomized plasma, but in low concentrations. The data support the concept that the major part of plasma prorenin in intact rats originates from the kidneys. The previously published values for prorenin in intact rats were correct, whereas those in 24-h nephrectomized rats were too high. If N-ethylmaleimide is added to our previously published method for rat prorenin, it overcomes the three known problems with prorenin determination in rat plasma: trypsin generation of angiotensin I immunoreactive material; trypsin destruction of angiotensinogen; and interference in trypsin-activated nephrectomized plasma of a sulphydryl enzyme, which generates an angiotensin-I-like material.
旨在证明24小时肾切除大鼠的血浆中是否存在肾素原。其存在及浓度目前仍存在争议。
测定完整大鼠和24小时肾切除大鼠血浆肾素抑制的50%抑制浓度（IC50）值。使用了强效且特异的大鼠肾素抑制剂CH-732。
采用我们之前发表的测定大鼠肾素原的方法。其特点是在肾素孵育步骤之前去除干扰性的胰蛋白酶形成的血管紧张素I免疫反应性物质。
通过CH-732抑制判断，24小时肾切除血浆中胰蛋白酶激活的肾素原样活性仅在较小程度上归因于真正的肾素原。肾素原样活性的主要部分归因于一种迄今未知的巯基酶，它可被N-乙基马来酰亚胺阻断。在正常血浆中，所有肾素原都是真正的肾素原。24小时肾切除大鼠中真正肾素原的血浆浓度约为完整大鼠的10%。
肾切除血浆中确实存在肾素原，但浓度较低。这些数据支持了完整大鼠血浆中肾素原主要来源于肾脏的概念。之前发表的完整大鼠肾素原的值是正确的，而24小时肾切除大鼠的值则过高。如果将N-乙基马来酰亚胺添加到我们之前发表的大鼠肾素原测定方法中，它将克服大鼠血浆肾素原测定中已知的三个问题：胰蛋白酶生成血管紧张素I免疫反应性物质；胰蛋白酶破坏血管紧张素原；以及巯基酶对胰蛋白酶激活的肾切除血浆的干扰，该酶产生一种血管紧张素I样物质。
