Hsueh W A, Carlson E J, Dzau V J
J Clin Invest. 1983 Mar;71(3):506-17. doi: 10.1172/jci110795.
An inactive form of renin has been isolated from human plasma. It has been suggested that this may represent renin precursor secreted from the kidney. However, early studies failed to isolate inactive renin from human renal tissue. In this investigation, rapid processing of human kidney cortex at temperatures below 4 degrees C in the presence of protease inhibitors followed by cibacron-blue affinity chromatography allowed us to extract a totally inactive form of renal renin. Furthermore, we found that in kidney inactive renin constituted from 10 to as much as 50% of the total renin concentration. Biochemical characterization of the inactive renin from plasma and from kidney indicates that they are structural homologues and, when activated, have enzymatic properties that resemble active renal renin. Renal and plasma inactive renin were found to have the following properties in common: (a) a pH optimum of activation of 3.3; (b) reversible activation by acid dialysis on return to pH 7.4, 37 degrees C; (c) pH optima of enzyme activity of 7.8 with sheep angiotensinogen and 5.5 and 6.7 (biphasic) with human angiotensinogen; (d) Michaelis-Menten constants, Km, of 0.29-0.34 microM with sheep angiotensinogen, and 0.99-1.25 microM with human angiotensinogen; (e) an antibody to human renal renin mean inhibitory titer of 1:30,000 with 1 X 10(-4) Goldblatt units of activated renal or plasma inactive renin; (f) gel filtration profiles consisting of two peaks with apparent molecular weights of 56,000 +/- 1,500 and 49,200 +/- 1,000. Activation of plasma and kidney inactive renin by acid plus renal kallikrein was not accompanied by a change in gel filtration elution patterns. To determine whether inactive renin is released by the kidney, we measured inactive renin in samples obtained simultaneously from both the renal veins and inferior vena cava below the origin of the renal veins. In eight consecutive patients, inactive renin concentration was significantly higher in renal venous blood than in inferior vena caval blood. These data indicate that human kidney contains and secretes significant quantities of inactive renin. Thus, the kidney appears to be a major source of inactive renin in human plasma.
已从人血浆中分离出一种无活性形式的肾素。有人提出，这可能代表肾脏分泌的肾素前体。然而，早期研究未能从人肾组织中分离出无活性肾素。在本研究中，在蛋白酶抑制剂存在的情况下，于4℃以下对人肾皮质进行快速处理，随后进行汽巴蓝亲和层析，使我们能够提取出一种完全无活性形式的肾肾素。此外，我们发现，在肾脏中，无活性肾素占总肾素浓度的10%至高达50%。对来自血浆和肾脏的无活性肾素进行的生化特性分析表明，它们是结构同源物，激活后具有类似于活性肾肾素的酶促特性。发现肾和血浆无活性肾素具有以下共同特性：(a)激活的最适pH为3.3；(b)通过酸透析恢复至pH 7.4、37℃时可进行可逆激活；(c)以绵羊血管紧张素原为底物时酶活性的最适pH为7.8，以人血管紧张素原为底物时为5.5和6.7（双相）；(d)以绵羊血管紧张素原为底物时的米氏常数Km为0.29 - 0.34μM，以人血管紧张素原为底物时为0.99 - 1.25μM；(e)针对人肾肾素的抗体对1×10(-4) Goldblatt单位的激活肾或血浆无活性肾素的平均抑制效价为1:30,000；(f)凝胶过滤图谱由两个峰组成，表观分子量分别为56,000±1,500和49,200±1,000。酸加肾激肽释放酶对血浆和肾脏无活性肾素的激活并未伴随凝胶过滤洗脱模式的改变。为了确定无活性肾素是否由肾脏释放，我们测定了同时从肾静脉和肾静脉起始部下方的下腔静脉采集的样本中的无活性肾素。在连续8例患者中，肾静脉血中的无活性肾素浓度显著高于下腔静脉血中的浓度。这些数据表明，人肾脏含有并分泌大量无活性肾素。因此，肾脏似乎是人类血浆中无活性肾素的主要来源。
