Schulz R, Sakane Y, Berry C, Ghai R
Research Department, CIBA-GEIGY Corporation, Summit, New Jersey 07901.
J Enzyme Inhib. 1991;4(4):347-58. doi: 10.3109/14756369109030399.
Neutral endopeptidase 3.4.24.11 (NEP) has been identified as the major atrial natriuretic factor (ANF) degrading enzyme in rat kidney, therefore, suggesting a possible role for this enzyme in blood volume and pressure regulation. Various experimentally induced and genetically hypertensive rat models have been used to test NEP inhibitors. The presence of different isoforms of NEP in the various hypertensive rat models would have relevance when searching for novel NEP inhibitors. Therefore, we compared the properties of NEP in kidney cortex homogenates in order to test for possible differences in the following hypertensive rat models and their appropriate controls: spontaneously hypertensive rats (SHR), Wistar Kyoto strain (WKY), DOCA-salt hypertensive rats, and Sprague Dawley control rats (SD). No relevant differences were found when comparing the following parameters: (1) specific activity (mean: 204 U/mg protein), (2) Michaelis constant (mean: 280 microM), (3) IC50 of thiorphan (mean: 6.5 nM) and phosphoramidon (mean: 54 nM), (4) pH profiles (optimum at pH 8.0), (5) heat inactivation profiles (half-life 20 min at 65 degrees C), (6) immunotitration of kidney cortex homogenates, (7) molecular weight as determined by gel filtration (92,000 Dalton) and (8) affinity chromatography with concanavalin A. Without evidence for the presence of different NEP isoforms, it is unlikely that divergent findings in DOCA-salt rats and SHR using a given NEP inhibitor are due to isoforms of NEP.
中性内肽酶3.4.24.11（NEP）已被确定为大鼠肾脏中主要的心房利钠因子（ANF）降解酶，因此表明该酶在血容量和血压调节中可能发挥作用。各种实验诱导和基因高血压大鼠模型已被用于测试NEP抑制剂。在寻找新型NEP抑制剂时，各种高血压大鼠模型中NEP不同同工型的存在可能具有相关性。因此，我们比较了肾皮质匀浆中NEP的特性，以测试以下高血压大鼠模型及其相应对照中是否存在可能的差异：自发性高血压大鼠（SHR）、Wistar Kyoto品系（WKY）、去氧皮质酮盐高血压大鼠和Sprague Dawley对照大鼠（SD）。比较以下参数时未发现相关差异：（1）比活性（平均：204 U/mg蛋白质），（2）米氏常数（平均：280 microM），（3）硫磷酰胺的IC50（平均：6.5 nM）和磷酰胺脒（平均：54 nM），（4）pH曲线（pH 8.0时最佳），（5）热失活曲线（65℃下半衰期20分钟），（6）肾皮质匀浆的免疫滴定，（7）通过凝胶过滤测定的分子量（92,000道尔顿）和（8）伴刀豆球蛋白A亲和层析。由于没有证据表明存在不同的NEP同工型，因此使用给定NEP抑制剂在去氧皮质酮盐大鼠和SHR中得出的不同结果不太可能是由于NEP的同工型所致。
