Ackerly J A, Peach M J, Vaughan E D, Glenn A W
Endocrinology. 1980 Dec;107(6):1699-704. doi: 10.1210/endo-107-6-1699.
Bioassay studies have indicated that angiotensin I (Ang I), but not angiotensin II (Ang II), is degraded by the intact lung. The present study was an attempt to isolate and quantify pulmonary metabolites of Ang I. The pulmonary vascular bed of the rat was isolated and perfused at 4-6 ml/min (< 20 mm Hg) with oxygenated Krebs buffer containing 5% bovine serum albumin. [3H-Leu10]Ang I (3-10 ng) was administered, and pulmonary effluent samples were collected every 15 sec for 5 min. Peptides were isolated by Dowex chromatography and separated by thin layer chromatography. 3H-labeled peptides were eluted from the thin layer chromatography plate, and the Ang I and [des-Asp1]Ang I levels were estimated by RIA. These peptides were shown to be hydrolyzed by purified converting enzyme with the release of His-3H-Leu. About 25% of the [3H]Ang I administered was isolated as [3H-des-Asp1]Ang I, and this percentage increased to 33% after treatment with teprotide. These studies clearly demonstrate that [des-Asp1]Ang I is a major pulmonary metabolite of Ang I and suggest the presence of a pulmonary aminopeptidase which hydrolyzes Ang I but not Ang II.
生物测定研究表明，完整的肺可降解血管紧张素I（Ang I），而不是血管紧张素II（Ang II）。本研究旨在分离并定量Ang I的肺代谢产物。分离大鼠的肺血管床，以4 - 6毫升/分钟（<20毫米汞柱）的流速用含5%牛血清白蛋白的充氧 Krebs 缓冲液进行灌注。给予[3H - Leu10]Ang I（3 - 10纳克），每隔15秒收集一次肺流出液样本，共收集5分钟。通过Dowex柱色谱法分离肽段，并通过薄层色谱法进行分离。从薄层色谱板上洗脱3H标记的肽段，通过放射免疫分析法（RIA）估算Ang I和[des - Asp1]Ang I的水平。这些肽段显示可被纯化的转化酶水解，并释放出His - 3H - Leu。给予的[3H]Ang I中约25%被分离为[3H - des - Asp1]Ang I，用替普罗肽处理后，这一比例增至33%。这些研究清楚地表明，[des - Asp1]Ang I是Ang I的主要肺代谢产物，并提示存在一种可水解Ang I但不能水解Ang II的肺氨肽酶。
