Voelker J R, Cobb S L, Bowsher R R
Department of Medicine, Indiana University School of Medicine, Indianapolis 46202.
Clin Chem. 1994 Aug;40(8):1537-43.
To measure the octapeptide angiotensin II (Ang II) in plasma, we developed a sensitive, specific assay that interfaces solid-phase extraction, HPLC, and RIA. A reversed-phase HPLC system involving isocratic elution at 38 degrees C with a volatile mobile phase of acetonitrile and the ion-pairing reagent heptafluorobutyric acid produced baseline separation of angiotensin peptides. Ang II was collected as a single fraction, concentrated by evaporation to dryness, and measured by RIA after resuspension in RIA buffer. Even including column washing between sample injections to prevent carryover of plasma constituents, two plasma extracts could be processed per hour by HPLC. Assay validation experiments demonstrated < 2% cross-reactivity with Ang II-related peptides; a 75% recovery from plasma at physiological concentrations of Ang II; intra- and interassay precision (CVs) of 6.2% and 10.3%, respectively; and a lower limit of quantification of 1.3 ng/L. Two clinical protocols designed to measure plasma Ang II concentration under basal and stimulated conditions confirmed the utility of the assay.
为了测定血浆中的八肽血管紧张素II（Ang II），我们开发了一种灵敏、特异的检测方法，该方法结合了固相萃取、高效液相色谱（HPLC）和放射免疫分析（RIA）。一种反相HPLC系统，在38℃下采用乙腈和离子对试剂七氟丁酸的挥发性流动相进行等度洗脱，可实现血管紧张素肽的基线分离。Ang II作为单一馏分收集，通过蒸发浓缩至干，然后在重悬于RIA缓冲液后用RIA进行测定。即使包括在样品进样之间进行柱冲洗以防止血浆成分的残留，HPLC每小时也可处理两份血浆提取物。检测验证实验表明，该方法与Ang II相关肽的交叉反应率<2%；在Ang II生理浓度下，血浆回收率为75%；批内和批间精密度（CV）分别为6.2%和10.3%；定量下限为1.3 ng/L。两项旨在测量基础和刺激条件下血浆Ang II浓度的临床方案证实了该检测方法的实用性。
