Rolinski B, Sadri I, Bogner J, Goebel F D
Medizinische Poliklinik, University of Munich, Germany.
Res Exp Med (Berl). 1994;194(1):9-24. doi: 10.1007/BF02576362.
Endothelin-1 (ET-1) is a potent vasoconstrictor peptide apparently involved in a number of vascular diseases in man. Nonetheless, its determination in biological samples is difficult, and data on plasma or urine concentrations are controversial. We investigated different sample preparation procedures as well as different radioimmunoassays for their influence on ET-1 measurement. Recovery of ET-1 depended on the extraction procedure, the type and size of the extraction columns and on the biological matrix itself. Incomplete removal of matrix components by the extraction leads to the formation of particulate matter in the evaporated eluate. When dissolved in assay buffer, ET-1 was found to be absorbed to and only partly released from these particulates, so that it was not accessible for measurement in a radioimmunoassay. This was the case for all extraction procedures investigated except for that involving acetic acid. HPLC analysis of spiked samples revealed that ET-1 is in part degraded during extraction, most probably to Meth-sulphoxide ET-1. Dilution curves of synthetic pure ET-1 standards from different suppliers, prepared either in plasma with subsequent extraction or in assay buffer of the respective radioimmunoassay, resulted in considerable differences in the measured values for ET-1-immunoreactivity. Every radioimmunoassay tested had a specific pattern of recognizing different synthetic ET-1 standards. In conclusion, the measurement of ET-1-immunoreactivity is strongly influenced by the experimental conditions of sample preparation as well as by the radioimmunoassay employed.
内皮素 -1（ET -1）是一种强效血管收缩肽，显然与人类的多种血管疾病有关。尽管如此，在生物样品中测定它却很困难，而且关于血浆或尿液浓度的数据存在争议。我们研究了不同的样品制备程序以及不同的放射免疫测定法对ET -1测量的影响。ET -1的回收率取决于提取程序、提取柱的类型和大小以及生物基质本身。提取过程中基质成分去除不完全会导致蒸发洗脱液中形成颗粒物。当溶解在测定缓冲液中时，发现ET -1会吸附到这些颗粒物上且只有部分从颗粒物上释放出来，因此在放射免疫测定中无法进行测量。除了涉及乙酸的提取程序外，所有研究的提取程序都是这种情况。对加标样品的HPLC分析表明，ET -1在提取过程中部分降解，最有可能降解为甲硫氧化物ET -1。不同供应商的合成纯ET -1标准品的稀释曲线，无论是在血浆中制备随后提取，还是在各自放射免疫测定的测定缓冲液中制备，ET -1免疫反应性的测量值都存在相当大的差异。所测试的每种放射免疫测定都有识别不同合成ET -1标准品的特定模式。总之，ET -1免疫反应性的测量受到样品制备的实验条件以及所采用的放射免疫测定的强烈影响。
