A sensitive radioimmunoassay for immunoreactive somatostatin in extracted plasma: measurement and characterization of portal and peripheral plasma in the rat.
A sensitive radioimmunoassay for immunoreactive somatostatin in extracted plasma: measurement and characterization of portal and peripheral plasma in the rat.
复制标题
提取血浆中免疫反应性生长抑素的灵敏放射免疫测定法：大鼠门静脉和外周血浆的测量和表征。
作者：
Y. Patel;T. Wheatley;D. Fitz;G. Brock
未提取的大鼠血浆中免疫反应性生长抑素（IRS）的RIA已被证明是困难的，因为显着的示踪剂降解。在标准曲线管中存在0.1 ml血浆时，[Tyr 1 - 125 I]-生长抑素（SRIF）损伤超过80%，结合率仅为2.7%，而在无血浆缓冲液中为38%。血浆孵育后[Tyr 1 - 125 I]SRIF的Sephadex凝胶过滤显示，大部分放射性转化为无免疫反应性的低分子量片段。EDTA和特雷西洛不能阻止[Tyr 1 - 125 I]SRIF降解。在简单的一步法中，通过用酸-乙醇提取血浆克服了[Tyr 1 - 125 I]SRIF的破坏。采用该技术，从血浆中合成SRIF的回收率平均为93.8%。测定灵敏度为30 pg IRS/ ml血浆。与大鼠血液孵育的外源性SRIF在37 ℃下以17分钟的t/12和22 ℃下以76分钟的t/12迅速失活。门静脉血浆IRS水平平均为310 pg/ml（n = 18;范围，106-570 pg/ml），与IRS浓度一致。
The RIA of immunoreactive somatostatin (IRS) in unextracted rat plasma has proved difficult because of marked tracer degradation. The presence of 0.1 ml plasma in standard curve tubes resulted in more than 80% damage to [Tyr1-125I]-somatostatin (SRIF) and only 2.7% binding compared to 38% in plasma free buffer. Sephadex gel filtration of [Tyr1-125I]SRIF after plasma incubation showed that most of the radioactivity was converted to a lower molecular weight fragment with no immunoreactivity. EDTA and Trasylol did not prevent [Tyr1- 125I]SRIF degradation. Destruction of [Tyr1-125I]SRIF was overcome by extraction of plasma with acid-ethanol in a simple 1-step procedure. With this technique, recovery of synthetic SRIF from plasma averaged 93.8%. Assay sensitivity was 30 pg IRS/ ml plasma. Exogenous SRIF incubated with rat blood was rapidly inactivated with a t/12 of 17 min at 37 C and 76 min at 22 C. The mean portal plasma IRS level was 310 pg/ml (n = 18; range, 106–570 pg/ml), in good agreement with the IRS c...