IDENTIFICATION AND QUANTIFICATION OF RENIN AND PRORENIN IN THE BOVINE EYE
IDENTIFICATION AND QUANTIFICATION OF RENIN AND PRORENIN IN THE BOVINE EYE
复制标题
DOI：
10.1210/endo-126-3-1673
复制
发表时间：
1990-03-01
期刊：
影响因子：
4.8
通讯作者：
SCHALEKAMP, MADH
中科院分区：
文献类型：
--
作者：
DEINUM, J;DERKX, FHM;SCHALEKAMP, MADH
血管紧张素-II是肾素-血管紧张素系统的最重要的生物活性产物，据报道在新生血管形成中起作用，并且在人眼的玻璃体中发现了前肾素，特别是在受增殖性糖尿病视网膜病变（一种以新生血管形成为特征的疾病）影响的人眼中。在这些眼睛的前肾素水平，相对于血浆白蛋白，高于眼睛没有新血管形成。这些结果表明，眼内存在一个肾素-血管紧张素系统，它可能参与了糖尿病视网膜新生血管的发展。在这项研究中，血管紧张素-I-生成活性测定牛眼房水和玻璃体和牛视网膜，色素上皮脉络膜和前葡萄膜的提取物之前和之后，这些提取物的程序已知转换为肾素原。通过在37 ℃下与来自肾切除大鼠的血浆在pH范围为5.0-8.5下孵育来进行测量。眼样品中的真肾素可通过α-葡萄糖苷酶从非肾素酸性蛋白酶中分离出来。pH3.5下的酪蛋白-琼脂糖亲和柱层析;真凝乳酶不与柱结合，而酸性蛋白酶则与柱结合。真正的肾素通过其相对高的生成血管紧张素-I的最适pH（6.5-7.0）、其被特异性肾素抗血清完全抑制以及其对特异性肾素抑制剂的高亲和力而被进一步鉴定。超过75%的血管紧张素-I生成活性的眼部样本组成的真正的肾素。房水、玻璃体和眼组织中约90%或更多的总肾素（肾素加原肾素）不能用滞留血浆解释。总肾素在房水和玻璃体中的肾素接近检测限的血管紧张素-I生成活性的测定。在玻璃体中，前肾素占总肾素的99%，在视网膜中占81%，而在色素上皮-脉络膜和前葡萄膜中不到50%。眼液中前肾素浓度梯度为后玻璃体>前玻璃体>房水，提示眼外前肾素主要来源于后眼。这些数据支持眼睛局部肾素和/或原肾素合成的论点，并与其他组织的观察结果一致，即肾外肾素合成通常主要或完全与原肾素释放到细胞外液中有关。
Angiotensin-II, the most important biologically active product of the renin-angiotensin system, has been reported to play a role in neovascularization, and prorenin has been found in the vitreous of human eyes, particularly in those affected by proliferative diabetic retinopathy, a disease characterized by neovascularization. The prorenin level in these eyes was, relative to that of plasma albumin, higher than in eyes without neovascularization. These findings suggested that an intraocular renin-angiotensin system exists, which might be involved in the development of retinal neovascularization in diabetes mellitus. In this study angiotensin-I-generating activity was measured in bovine aqueous humor and vitreous and in extracts of bovine retina, pigment epithelium-choroid, and anterior uveal tract before and after subjecting these extracts to procedures known to convert prorenin to renin. The measurements were made by incubation at 37 C with plasma from nephrectomized rats at pH ranging from 5.0-8.5. True renin in the ocular samples could be separated from nonrenin acid protease by .alpha.-casein-Sepharose affinity column chromatography at pH 3.5; true renin did not bind to the column, whereas acid protease did. True renin was further identified by its relatively high pH optimum (6.5-7.0) for angiotensin-I generation, its complete inhibition with specific renin antiserum, and its high affinity for specific renin inhibitors. More than 75% of angiotensin-I-generating activity of the ocular samples consisted of true renin. Approximately 90% or more of total renin (renin plus prorenin) in aqueous humor, vitreous, and ocular tissue could not be explained by trapped plasma. Total renin in aqueous humor and renin in vitreous were near the detection limit of the assay of angiotensin-I-generating activity. In vitreous prorenin comprised 99% of the total renin, in retina 81%, and in pigment epithelium-choroid and anterior uveal tract less than 50%. Prorenin in ocular fluids showed a concentration gradient, posterior vitreous > anterior vitreous > aqueous humor, suggesting that the main source of extracellular prorenin was in the posterior eye. These data support the contention of local renin and/or prorenin synthesis in the eye and are in accordance with the observations in other tissues that extrarenal synthesis of renin is often associated with the release of mainly, or exclusively, prorenin into extracellular fluid.